Meaning of pll. PLL: Decoding the Versatile Acronym in Technology and Beyond

What does PLL stand for in various fields. How is PLL used in electronics and telecommunications. Why is PLL important in modern technology. What are the applications of PLL in different industries.

The Many Faces of PLL: Exploring Its Diverse Meanings

PLL is a versatile acronym that carries different meanings across various fields and industries. Understanding these diverse interpretations is crucial for effective communication in specialized contexts. Let’s explore some of the most common and significant definitions of PLL:

• Phase Locked Loop (Electronics and Telecommunications)
• Pall Corporation (Business)
• Prescribed Load List (Military)
• Provision for Loan Loss (Accounting)
• Paralegal Legal Litigator (Legal)
• Premier Lacrosse League (Sports)
• Pretty Little Liars (Entertainment)

Each of these definitions represents a unique application or concept within its respective field. The context in which PLL is used determines its specific meaning, highlighting the importance of clear communication when using acronyms.

Phase Locked Loop: The Cornerstone of Modern Electronics

In the realm of electronics and telecommunications, PLL most commonly stands for Phase Locked Loop. This fundamental concept plays a crucial role in various electronic systems and devices.

What is a Phase Locked Loop?

A Phase Locked Loop is a control system that generates an output signal whose phase is related to the phase of an input signal. It consists of three main components:

1. Phase Detector
2. Low Pass Filter
3. Voltage Controlled Oscillator (VCO)

These components work together to synchronize the output signal with the input signal, maintaining a constant phase relationship between them.

How does a Phase Locked Loop work?

The operation of a PLL can be summarized in the following steps:

1. The phase detector compares the input signal with the output of the VCO.
2. It generates an error signal proportional to the phase difference.
3. The low pass filter smooths out the error signal.
4. The filtered signal adjusts the VCO frequency.
5. This process continues until the VCO output matches the input signal in both frequency and phase.

This feedback mechanism allows PLLs to track and lock onto specific frequencies with high precision, making them invaluable in numerous applications.

Applications of Phase Locked Loops in Modern Technology

Phase Locked Loops have found their way into a wide array of electronic devices and systems, revolutionizing various aspects of modern technology. Some key applications include:

• Frequency synthesis in radio and wireless communications
• Clock recovery in digital communications
• Motor speed control
• Demodulation of FM signals
• Noise reduction in audio systems
• Synchronization in digital circuits

These applications demonstrate the versatility and importance of PLLs in ensuring precise timing and synchronization across different technological domains.

PLL in Business: Pall Corporation and Its Impact

In the business world, PLL is often associated with Pall Corporation, a global leader in filtration, separation, and purification technologies. Founded in 1946, Pall Corporation has established itself as a key player in various industries, including:

• Aerospace
• Biopharmaceuticals
• Food and Beverage
• Microelectronics
• Industrial Manufacturing

The company’s innovative solutions have contributed significantly to advancements in filtration technology, impacting diverse sectors from healthcare to environmental protection.

How has Pall Corporation influenced industry standards?

Pall Corporation’s commitment to research and development has led to numerous breakthroughs in filtration technology. Their innovations have:

• Improved product quality and safety in manufacturing processes
• Enhanced efficiency in biopharmaceutical production
• Reduced environmental impact in industrial operations
• Advanced water purification techniques

These contributions have not only set new industry standards but also addressed critical global challenges related to resource management and sustainability.

PLL in Military Operations: Prescribed Load List

In military contexts, PLL stands for Prescribed Load List, a critical component of logistics and supply chain management for armed forces. The Prescribed Load List is an inventory of essential spare parts and supplies that a military unit must maintain to ensure operational readiness.

Why is the Prescribed Load List important for military operations?

The PLL plays a crucial role in maintaining military effectiveness by:

• Ensuring quick repairs and maintenance of equipment
• Minimizing downtime during operations
• Reducing the need for external supply chains in remote locations
• Improving overall unit readiness and response times

By carefully managing their Prescribed Load List, military units can maintain high levels of operational efficiency and readiness, even in challenging environments.

PLL in Finance: Provision for Loan Loss

In the financial sector, particularly in banking and accounting, PLL often refers to Provision for Loan Loss. This is a crucial concept in risk management for financial institutions.

What is a Provision for Loan Loss?

A Provision for Loan Loss is an expense set aside as an allowance for uncollected loans and loan payments. It reflects the estimated amount of loans that may default or become uncollectible in the future.

How do financial institutions use Provision for Loan Loss?

Banks and other lending institutions use PLL to:

• Manage risk associated with their loan portfolios
• Comply with regulatory requirements
• Provide a more accurate picture of their financial health
• Prepare for potential economic downturns

By maintaining adequate Provisions for Loan Losses, financial institutions can better withstand economic shocks and maintain stability in the financial system.

PLL in Entertainment: Pretty Little Liars

In popular culture, particularly among younger audiences, PLL is often associated with the hit television series “Pretty Little Liars.” This American teen drama mystery thriller series, based on the book series by Sara Shepard, gained a massive following during its run from 2010 to 2017.

What made Pretty Little Liars a cultural phenomenon?

The success of Pretty Little Liars can be attributed to several factors:

• Intriguing mystery plot that kept viewers engaged
• Strong character development and relatable themes
• Effective use of social media to engage with fans
• Exploration of complex issues relevant to young adults

The show’s impact extended beyond television, influencing fashion trends, social media engagement, and even spawning spin-off series and books.

The Future of PLL: Emerging Trends and Applications

As technology continues to evolve, the applications and significance of PLL across various fields are likely to expand. Some emerging trends and potential future applications include:

Advanced Communication Systems

In the era of 5G and beyond, Phase Locked Loops will play an even more critical role in:

• Enabling higher data rates and lower latency
• Improving spectral efficiency in wireless networks
• Enhancing synchronization in distributed systems

Quantum Computing

As quantum computing technology advances, PLLs may find new applications in:

• Precise control of qubit states
• Synchronization of quantum gates
• Error correction in quantum circuits

Internet of Things (IoT)

The proliferation of IoT devices will likely lead to new uses for PLLs in:

• Low-power, high-precision timing for sensor networks
• Improved energy efficiency in smart devices
• Enhanced synchronization in distributed IoT systems

Artificial Intelligence and Machine Learning

PLLs may find novel applications in AI and ML hardware, potentially contributing to:

• Optimized timing in neuromorphic computing systems
• Improved performance of AI accelerators
• Enhanced energy efficiency in machine learning hardware

These emerging trends highlight the ongoing relevance and adaptability of PLL technology across various cutting-edge fields.

Navigating the Multi-Faceted World of PLL

The diverse meanings and applications of PLL across different industries underscore the importance of context in understanding and using acronyms effectively. Whether referring to Phase Locked Loops in electronics, Pall Corporation in business, or Pretty Little Liars in entertainment, PLL exemplifies how a simple three-letter acronym can encapsulate complex concepts and entities.

As we continue to push the boundaries of technology and innovation, it’s likely that new meanings and applications of PLL will emerge. Staying informed about these evolving definitions and their implications in various fields will be crucial for professionals and enthusiasts alike.

The multifaceted nature of PLL serves as a reminder of the interconnectedness of different industries and disciplines in our modern world. From the intricate workings of electronic circuits to the strategic decisions in corporate boardrooms, the concept of PLL touches numerous aspects of our daily lives, often in ways we may not immediately recognize.

As we look to the future, the continued relevance of PLL across diverse fields highlights the importance of interdisciplinary understanding and collaboration. Whether you’re an engineer working with Phase Locked Loops, a financial analyst dealing with Provisions for Loan Losses, or simply a fan of Pretty Little Liars, recognizing the broader context of PLL can provide valuable insights and foster innovation across boundaries.

In conclusion, the acronym PLL stands as a testament to the complexity and richness of our modern technological and cultural landscape. Its varied meanings and applications offer a unique lens through which we can explore the interconnections between different domains of knowledge and human endeavor. As we continue to innovate and push the boundaries of what’s possible, PLL will undoubtedly remain a significant concept, evolving and adapting to meet the challenges and opportunities of the future.

What does PLL stand for?

PLL	Phase Locked Loop Academic & Science » Electronics — and more…				Rate it:
PLL	Pall Corporation Business » NYSE Symbols				Rate it:
PLL	Phased Locked Loop Governmental » Military				Rate it:
PLL	Prescribed Load List Governmental » Military				Rate it:
PLL	Provision for Loan Loss Business » Accounting				Rate it:
PLL	Ponta Pelada, AM, Brazil Regional » Airport Codes				Rate it:
PLL	Paralegal Legal Litigator Business » Occupation & Positions				Rate it:
PLL	Plasma Lock Load Academic & Science » Electronics				Rate it:
PLL	Computer Associates Clipper Pre-Linked Library Computing » File Extensions				Rate it:
PLL	Permute Last Layer Miscellaneous » Unclassified				Rate it:
PLL	Permute lower layer Miscellaneous » Unclassified				Rate it:
PLL	Pretty Little Miscellaneous » Unclassified				Rate it:
PLL	ProLymphocytic Leukaemia Medical » Oncology				Rate it:
PLL	Permute left layer Miscellaneous » Unclassified				Rate it:
PLL	Premier Lacrosse League Sports » Lacrosse				Rate it:
PLL	Pretty Little Liars Internet » Chat				Rate it:
PLL	Papers on Language and Literature Academic & Science » Language & Literature				Rate it:
PLL	Permutate the last layer Miscellaneous » Unclassified				Rate it:
PLL	Permutation of Last Layer Miscellaneous » Unclassified				Rate it:
PLL	Phase Lock Loop Miscellaneous » Unclassified				Rate it:
PLL	Phase Locked Loops Miscellaneous » Unclassified				Rate it:
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PLL	Pre linked library Academic & Science » Libraries — and more. ..				Rate it:
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PLL	Private Law Libraries Academic & Science » Libraries				Rate it:

What does PLL mean? – PLL Definition – Meaning of PLL

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What does PLL mean? This could be the only web page dedicated to explaining the meaning of PLL (PLL acronym/abbreviation/slang word). Ever wondered what PLL means? Or any of the other 9309 slang words, abbreviations and acronyms listed here at Internet Slang? Your resource for web acronyms, web abbreviations and netspeak.   48px”> What is PLL? PLL is “Pretty Little Liar”   PLL Definition / PLL Means The definition of PLL is “Pretty Little Liar”   The Meaning of PLL org/Answer” eza=”wcalc:447px;wocalc:447px;hcalc:40px;rend_px_area:17880;cwidth:543px;;cheight:32px;;” cwidth=”543″> PLL means “Pretty Little Liar”   So now you know – PLL means “Pretty Little Liar” – don’t thank us. YW!   What does PLL mean? PLL is an acronym, abbreviation or slang word that is explained above where the PLL definition is given.   Other terms relating to ‘pretty’: BIMBO Stupid girl, usually pretty KAWAII Cute, pretty (Japanese) PDG Pretty Damn Good PDP Pretty Darn Precious PDQ Pretty Damn Quick PGDA Pretty Goddamn Awesome PGP Pretty Good Privacy (encryption) PHAT Pretty Hot And Tempting PRI Pretty PSR Pretty Standard, Really PURDY Pretty PYT Pretty Young Thing Other terms relating to ‘little’: BESITOS Little kisses (Spanish) BRONY Fan of My Little Pony DLS Dirty Little Secret ELH Every Little Helps LALB Laughing A Little Bit LBD Little Black Dress LBM Little Big Man LG Little Girl LIKKLE Little LIL Little MLP My Little Pony SALTS Smiled A Little Then Stopped SLH Santa’s Little Helper TLI Too Little Information

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Phase Locked Loops – an overview

Phase-Locked Loops

The phase-locked loop (PLL) is a frequency- and phase-sensitive feedback control circuit. It consists of three major parts: a mixer or phase detector, a LPF, and a VCO, as shown in Fig. 4.19. The signal from the VCO is compared to the input signal. If there is a frequency (or phase) difference between the two, an error signal is generated. This error signal is filtered by the LPF into a varying DC level and is used to control the VCO frequency. This is the feedback signal.

Figure 4.19. Phase-locked loop.

If the VCO frequency, f_o, differs from the input reference signal frequency, the phase detector sees this as a phase shift. This causes the phase detector to produce an error signal. This error signal is filtered into a varying DC signal that is used to control the VCO.

The VCO can be either a sine wave oscillator or a rectangular wave oscillator depending upon the desired waveshape of the output. In either case, the VCO output frequency is made directly proportional to the DC control voltage. There is a linear voltage-to-frequency relationship in the VCO. This means that changing the control voltage produces a proportional change in output frequency. If the voltage goes up, so does the frequency.

Now if an input reference signal whose frequency is near that of the VCO is applied to the PLL, the phase detector will produce an output voltage proportional to the frequency difference. This signal is filtered and the resulting DC control voltage is applied to the VCO. The control voltage is such that it forces the VCO frequency to move in a direction that reduces the error signal. This means that the VCO frequency will change until it is equal to the input reference signal frequency. When this happens, the two signals are synchronized or “locked.” The phase difference causes the phase detector to produce the DC voltage at the VCO input to keep the PLL locked to the input signal.

If the input reference signal changes, then the phase detector will recognize a frequency (or phase) difference between the input and the VCO output. As a result, the LPF will produce a different DC control signal that will force the VCO to change such that it is equal to the new input frequency. As you can see then, the PLL will “track” an input signal frequency as it changes.

The range of frequencies over which the PLL will track an input signal and remain locked is known as the lock range. This is a range of frequencies above and below the VCO free running frequency. The PLL can track and “lock” to any input frequency in this range. If an input signal out of the lock range is applied, the PLL will not synchronize.

If the input signal is initially outside of the lock range, the PLL will not lock. But, the PLL will jump into a locked condition as soon as the input frequency gets close to the VCO frequency. In other words, the PLL will “capture” the incoming signal if it is close enough to the VCO frequency. Once the input signal is captured, the PLL is locked and will track further changes in the input signal frequency.

The range of frequencies over which a PLL can capture a signal is known as the capture range. Like the lock range, it too is centered on the free running frequency. But the capture range is narrower than the lock range. The PLL acts as a frequency sensitive circuit over a narrow range of frequencies.

Since the PLL will only capture and lock on to input signals within a certain narrow band, the PLL acts like a band-pass filter. For that reason, the PLL is an excellent signal conditioner. You can take a noisy input signal or one with undesirable interference on it and filter it with a PLL. The PLL will lock on to only the desired frequency component of the input. The VCO reproduces the input signal at the same frequency but with the noise and interference removed. The PLL not only cleans up a signal but also can track it if its frequency changes.

The PLL is widely used for a variety of purposes. It is used to recover the clock signal in some wireless applications. It is used to recover the original signal in frequency modulation radio. It is used to multiply a frequency by a fixed factor. It can be used for motor speed control. Almost all electronic products of some kind contain a PLL.

Phase Locked Loop – an overview

Integer or Fractional?

The PLL architecture in Figure 10.6 is called an integer-N PLL. It is a simple and elegant architecture, and you can use it to generate any frequency that can be expressed as N × F_IN/R. Suppose that you have a 10-MHz reference frequency and you want to be able to tune the PLL output to around 500 MHz with a resolution of 1 kHz. The 1 kHz is called the channel spacing. Then the solution will be to set the R divider to 10,000 (i.e., 10 MHz/1 kHz). F_OUT is N × F_IN/R, which translates to N × 1 kHz. So the PLL will generate a 500-MHz signal if you set N = 500,000, or a 500-MHz + 1-kHz signal with N = 500,001, and so on. With an integer-N PLL, the rule is that the PFD frequency must be equal to the desired channel spacing. The required channel is then selected with the N divider.

Integer-N PLL chips are used in many products, but they have two fundamental issues linked to the rule. The first is lock time. In the previous example, the desired channel spacing was 1 kHz, giving a 1-kHz PFD frequency. Because the output of the PFD contains spikes of energy at the 1-kHz frequency, the low-pass filter between the PFD and the VCO must have a cutoff frequency that is significantly lower than 1 kHz in order to reject this noise. Typically, a good starting point is to set the loop filter bandwidth at 10% of the PFD frequency, so let’s assume that we use a 100-Hz filter.

What happens if you reprogram the N divider to switch the PLL to another frequency? The output of the PFD will change, but this analog signal will have to pass through the 100-Hz low-pass filter prior to changing the VCO frequency, which will take time because the filter is filtering out all quick variations. The PLL will lock to the new frequency, but probably some hundreds of milliseconds later. So with an integer-N PLL you have the choice between small frequency steps and fast lock time, not both.

The second issue with integer-N PLLs is a little less straightforward and related to phase noise. Basically, a PLL “multiplies” the PFD frequency by N. As you have seen, in order to have small frequency steps, you need a low PFD frequency, which means you need high values for N. Unfortunately, the phase detector is not a perfect device, so it generates some phase noise, which is unfortunately multiplied by N. Trust me, the PFD noise is increased by 20 log(N) in decibels, so it is far higher if you need to increase the N divider ratio. With an integer-N PLL, small frequency steps will always mean a more noisy output and a longer lock time. Life is difficult.

Fortunately, engineers have developed a new kind of PLL that doesn’t have these intrinsic limitations: so-called fractional-N PLLs. The idea is simple. A fractional-N PLL allows integer values for the N divider as well as fractional values. That’s a great idea. Through fractional-N PLLs the same channel spacing can be achieved with higher values for the PFD frequency, giving a quicker lock time and far lower noise.

Let’s take the previous example and assume that you have a fractional-N chip enabling a 0.01 resolution for N. You can then use a PFD frequency of 100 kHz (compared to 1 kHz with the integer-N PLL). An output frequency of 500 MHz + 1 kHz would be achieved with N = 5000.01; the loop filter would be 50 kHz and not 500 Hz (providing a 100× improvement in lock time), and the noise due to the PFD would be reduced by 20 log(100) = 40 dB. This seems magical, but nothing is free. No one has found a way to build a perfect fractional frequency divider on silicon (at megahertz or gigahertz speeds).

The trick used by actual fractional-N chips is to dynamically switch N between two integer values (e.g., 5000 and 5001 in this example) with a time ratio proportional to the designed fractional value. Note that 99% of the time with N = 5000 and 1% of the time with N = 5001, roughly a 5000.01 divide ratio is achieved. Unfortunately, this introduces some noise on the PFD output, which can generate nasty spurious frequencies on the output spectrum. Moreover, because of implementation restrictions, a fractional-N chip is more complex to program and can’t usually generate any arbitrary frequency.

PLL Meanings | What Does PLL Stand For?

43	PLL	Phase Locked Loop+ 3 variantsTechnology, Computing, Programming	Technology, Computing, Programming
10	PLL	Permutation of Last Layer Cubing, Cube, Layer	Cubing, Cube, Layer
8	PLL	Posterior Longitudinal Ligament Medical, Neurosurgery, Ligament	Medical, Neurosurgery, Ligament
8	PLL	Potential Loss of Life Engineering, Safety, Petrophysics	Engineering, Safety, Petrophysics
8	PLL	Prelinked Library Computing, Programming, Technology	Computing, Programming, Technology
5	PLL	Permutation of the Last Layer Cubing, Cube, Layer	Cubing, Cube, Layer
5	PLL	Poly-L-lysineChemistry, Medical	Chemistry, Medical
4	PLL	Permute Last Layer Cubing, Cube, Layer	Cubing, Cube, Layer
4	PLL	Prescribed Load List Military, Army, Maintenance	Military, Army, Maintenance
4	PLL	Pretty Little Liar Liar, Episode, Girl	Liar, Episode, Girl
4	PLL	Prolymphocytic Leukemia Medical, Pathology, Hematology	Medical, Pathology, Hematology
3	PLL	Posterior Lateral Line Medical, Biology	Medical, Biology
2	PLL	Air Pal Airline, ICAO Airline Code, Airline Code	Airline, ICAO Airline Code, Airline Code
2	PLL	Alginate-poly-L-lysineBioengineering, Biomedical Engineering, Medical	Bioengineering, Biomedical Engineering, Medical
2	PLL	Pall Corp.
2	PLL	Papua New Guinea Labour Law Jurisprudence	Jurisprudence
2	PLL	Par Labu Latviju

Phase-Locked Loop (PLL) Fundamentals | Analog Devices

Abstract:

Phase-locked loop (PLL) circuits exist in a wide variety of high frequency applications, from simple clock clean-up circuits, to local oscillators (LOs) for high performance radio communication links, and ultrafast switching frequency synthesizers in vector network analyzers (VNA). This article explains some of the building blocks of phase locked loop circuits with references to each of these applications, in turn, to help guide the novice and phase locked loop expert alike in navigating part selection and the trade-offs inherent for each different application. The article references the Analog Devices ADF4xxx and HMCxxx family of PLLs and voltage controlled oscillators (VCOs), and uses ADIsimPLL (Analog Devices in-house PLL circuit simulator) to demonstrate these different circuit performance parameters.

Basic Configuration: Clock Clean-Up Circuit

In its most basic configuration, a phase-locked loop compares the phase of a reference signal (F_REF) to the phase of an adjustable feedback signal (RF_IN) F₀, as seen in Figure 1. In Figure 2 there is a negative feedback control loop operating in the frequency domain. When the comparison is in steady-state, and the output frequency and phase are matched to the incoming frequency and phase of the error detector, we say that the PLL is locked. For the purposes of this article we shall only consider a classical digital PLL architecture as implemented on the Analog Devices ADF4xxx family of PLLs.

The first essential element in this circuit is the phase frequency detector (PFD). The PFD compares the frequency and phase of the input to REF_IN to the frequency and phase of the feedback to RF_IN. The ADF4002 is a PLL that can be configured as a standalone PFD (with the feedback divider N = 1). As such, it can be used with a high quality voltage controlled crystal oscillator (VCXO) and a narrow low-pass filter to clean up a noisy REF_IN clock.

Figure. 1 Basic PLL configuration.Figure 2. Basic PLL configuration.

Phase Frequency Detector

Figure 3. Phase frequency detector.

The phase frequency detector in Figure 3 compares the input to F_REF at +IN and the feedback signal at –IN. It uses two D-type flip flops with a delay element. One Q output enables a positive current source, and the other Q output enables a negative current source. These current sources are known as the charge pump. For more details on PFD operation, consult “Phase-Locked Loops for High Frequency Receivers and Transmitters.”

Using this architecture, the input to +IN below is at a higher frequency than the –IN (Figure 4), and the resultant charge pump output is pumping current high, which, when integrated in the PLL low-pass filter, will push the tuning voltage of the VCO up. In this way, the –IN frequency will increase as the VCO increases, and the two PFD inputs will eventually converge or lock to the same frequency (Figure 5). If the frequency to –IN is higher than +IN, the reverse happens.

Figure 4. A PFD out of phase and frequency lock.Figure 5. Phase frequency detector, frequency, and phase lock.

Returning to our original example of the noisy clock that requires cleaning, the phase noise profile of the clock, free running VCXO, and closed-loop PLL can be modeled in ADIsimPLL.

Figure 6. Reference noise.Figure 7. Free running VCXO. Figure 8. Total PLL noise.

As can be seen with the ADIsimPLL plots shown, the noisy phase noise profile of the REF_IN (Figure 6) is filtered by the low-pass filter. All the in-band noise contributed by the PLL reference and PFD circuitry is filtered out by the low-pass filter, leaving only the much lower VCXO noise (Figure 7) outside the loop bandwidth (Figure 8). When the output frequency is equal to the input frequency it creates one of the simplest PLL configurations. Such a PLL is called a clock clean-up PLL. For clock clean-up applications such as these, narrow (<1 kHz) low-pass filter bandwidths are recommended.

High Frequency Integer-N Architecture

To generate a range of higher frequencies, a VCO is used, which tunes over a wider range than a VCXO. This is regularly used in frequency hopping or in spread spectrum frequency hopping (FHSS) applications. In such PLLs, the output is a high multiple of the reference frequency. Voltage controlled oscillators contain a variable tuning element, such as a varactor diode, which varies its capacitance with input voltage, allowing a tuneable resonant circuit, which permits a range of frequencies to be generated (Figure 9). The PLL can be thought of as a control system for this VCO.

A feedback divider is used to divide the VCO frequency to the PFD frequency, which allows a PLL to generate output frequencies that are multiples of the PFD frequency. A divider may also be used in the reference path, which permits higher frequency references to be used than the PFD frequency. A PLL like this is the ADF4108 from Analog Devices. The PLL counters are the second essential element to be considered in our circuit.

Figure 9. Voltage controlled oscillator.

The key performance parameters of PLLs are phase noise, unwanted by-products of the frequency synthesis process, or spurious frequencies (spurs for short). For integer-N PLLs, spurious frequencies are generated by the PFD frequency. A leakage current from the charge pump will modulate the tuning port of the VCO. This effect is lessened by the low-pass filter and the narrower this is, the greater the filtering of the spurious frequency. An ideal tone would have no noise or additional spurious frequency (Figure 10), but in practice phase noise appears as a skirt around a carrier, as shown in Figure 11. Single sideband phase noise is the relative noise power to the carrier in a 1 Hz bandwidth, specified at a frequency offset from the carrier.

Figure 10. Ideal LO spectrum.Figure 11. Single sideband phase noise.

Integer-N and Fractional-N Divider

For narrow-band applications, the channel spacing is narrow (typically <5 MHz) and the feedback counter, N, is high. Gaining high N values with a small circuit is achieved by the use of a dual modulus P/P + 1 prescaler, as seen in Figure 12, and allows N values to be computed with the calculation of N = PB + A, which, using the example of an 8/9 prescaler and an N value of 90, computes a value of 11 for B and 2 for A. The dual modulus prescaler will divide by 9 for A or two cycles. It will then divide by 8 for the remaining (B-A) or 9 cycles, as described in Table 1. The prescaler is generally designed using a higher frequency circuit technology, such as bipolar emitter coupled logic (ECL) circuits, while the A and B counters can take this lower frequency prescaler output and can be manufactured with lower speed CMOS circuitry. This reduces circuit area and power consumption. Low frequency clean up PLLs like the ADF4002 omit this prescaler.

Figure 12. PLL with dual modulus N counter.

Table 1. Dual Modulus Prescaler Operation

N Value	P/P + 1	B Value	A Value
90	9	11	2
81	9	10	1
72	8	9	0
64	8	8	0
56	8	7	0
48	8	6	0
40	8	5	0
32	8	4	0
24	8	3	0
16	8	2	0
8	8	1	0
0	8	0	0

The in-band (inside the PLL loop filter bandwidth) phase noise is directly influenced by the value of N, and in-band noise is increased by 20log (N). So, for narrow-band applications in which the N value is high, the in-band noise is dominated by the high N value. A system that permits a much lower N value, but still permits fine resolution is enabled by a fractional-N synthesizer, such as the ADF4159 or HMC704. In this manner, the in-band phase noise can be greatly reduced. Figures 13 through 16 illustrate how this is achieved. In these examples, two PLLs are used to generate frequencies suitable for a 5G systems local oscillator (LO) in a range between 7.4 GHz to 7.6 GHz, with 1 MHz of channel resolution. The ADF4108 is used in an integer-N configuration (Figure 13) and the HMC704 is used in a fractional-N configuration. The HMC704 (Figure 14) can be used with a 50 MHz PFD frequency, which lowers the N value and, hence, the in-band noise, while still permitting a 1 MHz (or indeed smaller) frequency step size—an improvement of 15 dB (at 8 kHz offset frequency) is noted (Figure 15 vs. Figure 16). The ADF4108, however, is forced to use a 1 MHz PFD to achieve the same resolution.

Care needs to be taken with fractional-N PLLs to ensure that spurious tones do not degrade system performance. On PLLs such as the HMC704, integer boundary spurs (generated when the fractional portion of the N value approaches 0 or 1, like 147.98 or 148.02 are very close to the integer value of 148) generate the most concern. This can be mitigated by buffering the VCO output to the RF input, and/or careful frequency planning in which the REF_IN can be changed to avoid these more problematic frequencies.

Figure 13. Integer N PLL.

Figure 14. Fractional-N PLL.

Figure 15. Integer N PLL in-band phase noise.

Figure 16. Fractional-N PLL in-band phase noise.

For the majority of PLLs the in-band noise is highly dependent on the N value, and also on the PFD frequency. Subtracting 20log (N) and 10log (F_PFD) from the flat portion of an in-band phase noise measurement yields the figure of merit (FOM). A common metric for choosing PLLs is to compare the FOM. Another factor that influences the in-band noise is the 1/f noise, which is dependent on the output frequency of the device. The FOM contribution and the 1/f noise, together with the reference noise, dominate the in-band noise of a PLL system.

Narrow-Band LO for 5G Communications

For communication systems, the chief specifications from the PLL perspective are error vector magnitude (EVM) and VCO blocking specifications. EVM is similar in scope to integrated phase noise, which considers the noise contribution over a range of offsets. For the 5G system listed earlier, the integration limits are quite wide, starting at 1 kHz and continuing to 100 MHz. EVM can be thought of as a percentage degradation of a perfectly modulated signal from its ideal point expressed as a percentage (Figure 17). In a similar manner, integrated phase noise integrates the noise power at different offsets from the carrier and expresses this noise as a dBc number compared to the output frequency. ADIsimPLL can be configured to calculate the EVM, integrated phase noise, and rms phase error and jitter. Modern signal source analyzers will also include these numbers at the push of a button (Figure 18). As modulation schemes increase in density, EVM becomes critical. For 16-QAM, the required minimum EVM according to ETSI specification 3GPP TS 36.104 is 12.5%. For 64-QAM, the requirement is 8%. However, since EVM is comprised of various other nonideal parameters due to power amplifier distortion and unwanted mixer products, the integrated noise (in dBc) is usually defined separately.

Figure 17. Phase error visualization.

Figure 18. Signal source analyzer plot.

VCO blocking specifications are very important in cellular systems that need to account for the presence of strong transmissions. If a receiver signal is weak, and if the VCO is too noisy, then the nearby transmitter signal can mix down and drown out the wanted signal (Figure 19). The illustration in Figure 19 demonstrates how the nearby transmitter (800 kHz away) transmitting at –25 dBm power could, if the receiver VCO is noisy, swamp the wanted signal at –101 dBm. These specifications form part of a wireless communications standard. The blocking specifications directly influence the performance requirement of the VCO.

Figure 19. VCO noise blockers.

Voltage Controlled Oscillators (VCOs)

The next PLL circuit element to be considered in our circuit is the voltage controlled oscillator. With VCOs, a fundamental trade-off between phase noise, frequency coverage, and power consumption is necessary. The higher the quality factor (Q) of the oscillator, the lower the VCO phase noise is. However, higher Q circuits have narrower frequency ranges. Increasing the power supply will also lower the phase noise. Looking at the Analog Devices family of VCOs, the HMC507 covers a range of 6650 MHz to 7650 MHz and the VCO noise at 100 kHz is approximately –115 dBc/Hz. By contrast, the HMC586 covers a full octave from 4000 MHz to 8000 MHz, but has higher phase noise of –100 dBc/Hz. One strategy for minimizing phase noise in such VCOs is to increase the voltage tuning range of the V_TUNE to the VCO (up to 20 V or greater). This increases PLL circuit complexity, as most PLL charge pumps can only tune to 5 V, so an active filter using operational amplifiers is used to increase the tuning voltage of the PLL circuit on its own.

Multiband Integrated PLLs and VCOs

Another strategy to increase frequency coverage without degrading VCO phase noise is to use a multiband VCO, in which overlapping frequency ranges are used to cover an octave of frequency range, and lower frequencies can be generated by using frequency dividers at the output of the VCO. Such a device is the ADF4356, which uses four main VCO cores each with 256 overlapping frequency ranges. The internal reference and feedback frequency dividers are used by the device to choose the appropriate VCO band, a process known as VCO band select or autocalibration.

The wide tuning range of the multiband VCOs makes them suitable for use in wideband instrumentation, in which they generate a wide range of frequencies. The 39 bits of fractional-N resolution also makes them ideal candidates for these precise frequency applications. In instruments such as vector network analyzers, ultrafast switching speed is essential. This can be achieved by using a very wide low-pass filter bandwidth, which tunes to final frequency very quickly. The automatic frequency calibration routine can be bypassed in these applications by using a look-up table with the frequency values directly programmed for each frequency, true single core wideband VCOs like the HMC733 can also be used with less complexity.

For phase-locked loop circuits, the bandwidth of the low-pass filter has a direct influence on the settling time of the system. The low-pass filter is the final element in our circuit. If settling time is critical, the loop bandwidth should be increased to the maximum bandwidth permissible for achieving stable lock and meeting phase noise and spurious frequency targets. The narrow-band demands in a communications link mean the optimal bandwidth of the low-pass filter for minimum integrated noise (between 30 kHz to 100 MHz) is about 207 kHz (Figure 20) using the HMC507. This provides approximately –51 dBc of integrated noise and achieves frequency lock to within 1 kHz error in about 51 µs (Figure 22).

By contrast, the wideband HMC586 (covering from 4 GHz to 8 GHz) achieves the optimum rms phase noise with a wider bandwidth closer to 300 kHz bandwidth (Figure 21), achieving –44 dBc of integrated noise. However, it achieves frequency lock to the same specification in less than 27 µs (Figure 23). Correct part selection and the surrounding circuit design are all critical for achieving the best outcome for the application.

Figure 20. Phase noise HMC704 plus HMC507.

Figure 21. Phase noise HMC704 plus HMC586.

Figure 22. Frequency settling: HMC704 plus HMC507.

Figure 23. HMC704 plus HMC586.

Low Jitter Clocking

For high speed digital-to-analog converters (DACs) and high speed analog-to-digital converters (ADCs), a clean low jitter sampling clock is an essential building block. To minimize in band noise a low N value is desired; but to minimize spurious noise, integer N is preferred. Clocking tends to be fixed frequency so the frequencies can be chosen to ensure that the REF_IN frequency is an exact integer multiple of the input frequency. This ensures the lowest in-band PLL noise. The VCO (whether integrated or not) needs to be chosen to ensure that it is sufficiently low noise for the application, paying particular attention to the wideband noise. The low-pass filter then needs to be carefully placed to ensure that the in-band PLL noise will intersect with the VCO noise—this ensures lowest rms jitter. A low-pass filter with phase margin of 60° ensures lowest filter peaking, which minimizes jitter. In this manner, low jitter clocking falls in between the clock clean-up application of the first circuit discussed in this article, and the fast switching capability of the last circuit discussed.

For clocking circuits, the rms jitter of the clock is the key performance parameter. This can be estimated using ADIsimPLL or measured with a signal source analyzer. For high performance PLL parts like the ADF5356, a relatively wide low-pass filter bandwidth of 132 kHz, together with an ultralow REF_IN source like a Wenxel OCXO, allows the user to design clocks with rms jitter below 90 fs (Figure 26). Manipulating the placement of the PLL loop filter bandwidth (LBW) shows how decreasing it too much has an effect in which VCO noise begins to dominate at small offsets (Figure 24) where the in-band PLL noise would in fact be lower, and increasing it too much means the in-band noise is dominating at offsets where the VCO noise would instead be significantly lower (Figure 25).

Figure 24. LBW = 10 kHz, 331 fs jitter.

Figure 25. LBW = 500 kHz, 111 fs jitter.

Figure 26. LBW = 132 kHz, 83 fs jitter.

References

Collins, Ian. “Integrated PLLs and VCOs for Wireless Applications.” Radio Electronics, 2010.

Curtin, Mike and Paul O’Brien. “Phase-Locked Loops for High Frequency Receivers and Transmitters.” Analog Dialogue, Vol. 33, 1999.

ON THE MEANING OF “pll” IN THE BIBLE on JSTOR

Abstract

The basic meaning of pll in biblical Hebrew is found to be “accountable, responsible, liable.” The term appears to be most at home in legal or quasi-legal contexts, but may be extended to non-legal situations. Le sens premier de pll en hébreu biblique serait « être redevable, responsable, astreint ». Le terme, qui relève plutôt du vocabulaire juridique ou quasi-juridique, peut toutefois s’appliquer à des situations non juridiques.

Journal Information

The Biblical Review is the organ of the French Biblical and Archaeological School of Jerusalem. She publishes articles, columns, reviews, reports, on the study of the Bible and related disciplines: texts and inscriptions, history, geography, languages ​​of the ancient Near East, apocrypha, rabbinism, archeology of Palestine and neighboring countries (with illustrations), biblical, patristic and hermeneutical theology.

La Revue Biblique est l’organe de l’École Biblique et Archéologique Française de Jérusalem. Elle publie des articles, des chroniques, des recensions, des comptes rendus, concernant l’étude de la Bible et des disciplines annexes: textes et inscriptions, histoire, géographie, langues du Proche-Orient ancien, apocryphes, rabbinisme, archéologie de la Palestine et des pays voisins (avec illustrations), théologie biblique, patristique et herméneutique.

Publisher Information

Peeters is an international publishing house based in Leuven/Louvain, Belgium and established in 1857. It has since published some 6000 titles while each year about 200 new titles and 75 journals appear, both in print and online. Peeters was set up to serve the academic world by printing and publishing books in English, French, German and Dutch. Its major publication list contains books in theology, philosophy, ethics, classical studies, archaeology, history of art, medieval studies, oriental studies, linguistics and literature. Peeters publishes original research as well as bibliographic data, reviews and reference material. It is standard practice for each publication to be supervised by an editorial board which ensures high quality standards, based on independent reports.

Phase-Locked Loop (PLL) Fundamentals | Analog Devices

Abstract:

Phase-locked loop (PLL) circuits exist in a wide variety of high frequency applications, from simple clock clean-up circuits, to local oscillators (LOs) for high performance radio communication links, and ultrafast switching frequency synthesizers in vector network analyzers ( VNA). This article explains some of the building blocks of phase locked loop circuits with references to each of these applications, in turn, to help guide the novice and phase locked loop expert alike in navigating part selection and the trade-offs inherent for each different application.The article references the Analog Devices ADF4xxx and HMCxxx family of PLLs and voltage controlled oscillators (VCOs), and uses ADIsimPLL (Analog Devices in-house PLL circuit simulator) to demonstrate these different circuit performance parameters.

Basic Configuration: Clock Clean-Up Circuit

In its most basic configuration, a phase-locked loop compares the phase of a reference signal (F _REF ) to the phase of an adjustable feedback signal (RF _IN ) F ₀ , as seen in Figure 1.In Figure 2 there is a negative feedback control loop operating in the frequency domain. When the comparison is in steady-state, and the output frequency and phase are matched to the incoming frequency and phase of the error detector, we say that the PLL is locked. For the purposes of this article we shall only consider a classical digital PLL architecture as implemented on the Analog Devices ADF4xxx family of PLLs.

The first essential element in this circuit is the phase frequency detector (PFD).The PFD compares the frequency and phase of the input to REF _IN to the frequency and phase of the feedback to RF _IN . The ADF4002 is a PLL that can be configured as a standalone PFD (with the feedback divider N = 1). As such, it can be used with a high quality voltage controlled crystal oscillator (VCXO) and a narrow low-pass filter to clean up a noisy REF _IN clock.

Figure. 1 Basic PLL configuration. Figure 2. Basic PLL configuration.

Phase Frequency Detector

Figure 3.Phase frequency detector.

The phase frequency detector in Figure 3 compares the input to F _REF at + IN and the feedback signal at –IN. It uses two D-type flip flops with a delay element. One Q output enables a positive current source, and the other Q output enables a negative current source. These current sources are known as the charge pump. For more details on PFD operation, consult “Phase-Locked Loops for High Frequency Receivers and Transmitters.”

Using this architecture, the input to + IN below is at a higher frequency than the –IN (Figure 4), and the resultant charge pump output is pumping current high, which, when integrated in the PLL low-pass filter, will push the tuning voltage of the VCO up.In this way, the –IN frequency will increase as the VCO increases, and the two PFD inputs will eventually converge or lock to the same frequency (Figure 5). If the frequency to –IN is higher than + IN, the reverse happens.

Figure 4. A PFD out of phase and frequency lock. Figure 5. Phase frequency detector, frequency, and phase lock.

Returning to our original example of the noisy clock that requires cleaning, the phase noise profile of the clock, free running VCXO, and closed-loop PLL can be modeled in ADIsimPLL.

Figure 6. Reference noise.Figure 7. Free running VCXO.Figure 8. Total PLL noise.

As can be seen with the ADIsimPLL plots shown, the noisy phase noise profile of the REF _IN (Figure 6) is filtered by the low-pass filter. All the in-band noise contributed by the PLL reference and PFD circuitry is filtered out by the low-pass filter, leaving only the much lower VCXO noise (Figure 7) outside the loop bandwidth (Figure 8). When the output frequency is equal to the input frequency it creates one of the simplest PLL configurations.Such a PLL is called a clock clean-up PLL. For clock clean-up applications such as these, narrow (<1 kHz) low-pass filter bandwidths are recommended.

High Frequency Integer-N Architecture

To generate a range of higher frequencies, a VCO is used, which tunes over a wider range than a VCXO. This is regularly used in frequency hopping or in spread spectrum frequency hopping (FHSS) applications. In such PLLs, the output is a high multiple of the reference frequency. Voltage controlled oscillators contain a variable tuning element, such as a varactor diode, which varies its capacitance with input voltage, allowing a tuneable resonant circuit, which permits a range of frequencies to be generated (Figure 9).The PLL can be thought of as a control system for this VCO.

A feedback divider is used to divide the VCO frequency to the PFD frequency, which allows a PLL to generate output frequencies that are multiples of the PFD frequency. A divider may also be used in the reference path, which permits higher frequency references to be used than the PFD frequency. A PLL like this is the ADF4108 from Analog Devices. The PLL counters are the second essential element to be considered in our circuit.

Figure 9. Voltage controlled oscillator.

The key performance parameters of PLLs are phase noise, unwanted by-products of the frequency synthesis process, or spurious frequencies (spurs for short). For integer-N PLLs, spurious frequencies are generated by the PFD frequency. A leakage current from the charge pump will modulate the tuning port of the VCO. This effect is lessened by the low-pass filter and the narrower this is, the greater the filtering of the spurious frequency. An ideal tone would have no noise or additional spurious frequency (Figure 10), but in practice phase noise appears as a skirt around a carrier, as shown in Figure 11.Single sideband phase noise is the relative noise power to the carrier in a 1 Hz bandwidth, specified at a frequency offset from the carrier.

Figure 10. Ideal LO spectrum.Figure 11. Single sideband phase noise.

Integer-N and Fractional-N Divider

For narrow-band applications, the channel spacing is narrow (typically <5 MHz) and the feedback counter, N, is high. Gaining high N values ​​with a small circuit is achieved by the use of a dual modulus P / P + 1 prescaler, as seen in Figure 12, and allows N values ​​to be computed with the calculation of N = PB + A, which, using the example of an 8/9 prescaler and an N value of 90, computes a value of 11 for B and 2 for A.The dual modulus prescaler will divide by 9 for A or two cycles. It will then divide by 8 for the remaining (BA) or 9 cycles, as described in Table 1. The prescaler is generally designed using a higher frequency circuit technology, such as bipolar emitter coupled logic (ECL) circuits, while the A and B counters can take this lower frequency prescaler output and can be manufactured with lower speed CMOS circuitry. This reduces circuit area and power consumption. Low frequency clean up PLLs like the ADF4002 omit this prescaler.

Figure 12. PLL with dual modulus N counter.

Table 1. Dual Modulus Prescaler Operation

N Value	P / P + 1	B Value	A Value
90	9	11	2
81	9	10	1
72	8	9	0
64	8	8	0
56	8	7	0
48	8	6	0
40	8	5	0
32	8	4	0
24	8	3	0
16	8	2	0
8	8	1	0
0	8	0	0

The in-band (inside the PLL loop filter bandwidth) phase noise is directly influenced by the value of N, and in-band noise is increased by 20log (N).So, for narrow-band applications in which the N value is high, the in-band noise is dominated by the high N value. A system that permits a much lower N value, but still permits fine resolution is enabled by a fractional-N synthesizer, such as the ADF4159 or HMC704. In this manner, the in-band phase noise can be greatly reduced. Figures 13 through 16 illustrate how this is achieved. In these examples, two PLLs are used to generate frequencies suitable for a 5G systems local oscillator (LO) in a range between 7.4 GHz to 7.6 GHz, with 1 MHz of channel resolution. The ADF4108 is used in an integer-N configuration (Figure 13) and the HMC704 is used in a fractional-N configuration. The HMC704 (Figure 14) can be used with a 50 MHz PFD frequency, which lowers the N value and, hence, the in-band noise, while still permitting a 1 MHz (or indeed smaller) frequency step size — an improvement of 15 dB (at 8 kHz offset frequency) is noted (Figure 15 vs. Figure 16). The ADF4108, however, is forced to use a 1 MHz PFD to achieve the same resolution.

Care needs to be taken with fractional-N PLLs to ensure that spurious tones do not degrade system performance. On PLLs such as the HMC704, integer boundary spurs (generated when the fractional portion of the N value approaches 0 or 1, like 147.98 or 148.02 are very close to the integer value of 148) generate the most concern. This can be mitigated by buffering the VCO output to the RF input, and / or careful frequency planning in which the REF _IN can be changed to avoid these more problematic frequencies.

Figure 13. Integer N PLL.

Figure 14. Fractional-N PLL.

Figure 15. Integer N PLL in-band phase noise.

Figure 16. Fractional-N PLL in-band phase noise.

For the majority of PLLs the in-band noise is highly dependent on the N value, and also on the PFD frequency. Subtracting 20log (N) and 10log (F _PFD ) from the flat portion of an in-band phase noise measurement yields the figure of merit (FOM). A common metric for choosing PLLs is to compare the FOM.Another factor that influences the in-band noise is the 1 / f noise, which is dependent on the output frequency of the device. The FOM contribution and the 1 / f noise, together with the reference noise, dominate the in-band noise of a PLL system.

Narrow-Band LO for 5G Communications

For communication systems, the chief specifications from the PLL perspective are error vector magnitude (EVM) and VCO blocking specifications. EVM is similar in scope to integrated phase noise, which considers the noise contribution over a range of offsets.For the 5G system listed earlier, the integration limits are quite wide, starting at 1 kHz and continuing to 100 MHz. EVM can be thought of as a percentage degradation of a perfectly modulated signal from its ideal point expressed as a percentage (Figure 17). In a similar manner, integrated phase noise integrates the noise power at different offsets from the carrier and expresses this noise as a dBc number compared to the output frequency. ADIsimPLL can be configured to calculate the EVM, integrated phase noise, and rms phase error and jitter.Modern signal source analyzers will also include these numbers at the push of a button (Figure 18). As modulation schemes increase in density, EVM becomes critical. For 16-QAM, the required minimum EVM according to ETSI specification 3GPP TS 36.104 is 12.5%. For 64-QAM, the requirement is 8%. However, since EVM is comprised of various other nonideal parameters due to power amplifier distortion and unwanted mixer products, the integrated noise (in dBc) is usually defined separately.

Figure 17.Phase error visualization.

Figure 18. Signal source analyzer plot.

VCO blocking specifications are very important in cellular systems that need to account for the presence of strong transmissions. If a receiver signal is weak, and if the VCO is too noisy, then the nearby transmitter signal can mix down and drown out the wanted signal (Figure 19). The illustration in Figure 19 demonstrates how the nearby transmitter (800 kHz away) transmitting at –25 dBm power could, if the receiver VCO is noisy, swamp the wanted signal at –101 dBm.These specifications form part of a wireless communications standard. The blocking specifications directly influence the performance requirement of the VCO.

Figure 19. VCO noise blockers.

Voltage Controlled Oscillators (VCOs)

The next PLL circuit element to be considered in our circuit is the voltage controlled oscillator. With VCOs, a fundamental trade-off between phase noise, frequency coverage, and power consumption is necessary. The higher the quality factor (Q) of the oscillator, the lower the VCO phase noise is.However, higher Q circuits have narrower frequency ranges. Increasing the power supply will also lower the phase noise. Looking at the Analog Devices family of VCOs, the HMC507 covers a range of 6650 MHz to 7650 MHz and the VCO noise at 100 kHz is approximately –115 dBc / Hz. By contrast, the HMC586 covers a full octave from 4000 MHz to 8000 MHz, but has higher phase noise of –100 dBc / Hz. One strategy for minimizing phase noise in such VCOs is to increase the voltage tuning range of the V _TUNE to the VCO (up to 20 V or greater).This increases PLL circuit complexity, as most PLL charge pumps can only tune to 5 V, so an active filter using operational amplifiers is used to increase the tuning voltage of the PLL circuit on its own.

Multiband Integrated PLLs and VCOs

Another strategy to increase frequency coverage without degrading VCO phase noise is to use a multiband VCO, in which overlapping frequency ranges are used to cover an octave of frequency range, and lower frequencies can be generated by using frequency dividers at the output of the VCO …Such a device is the ADF4356, which uses four main VCO cores each with 256 overlapping frequency ranges. The internal reference and feedback frequency dividers are used by the device to choose the appropriate VCO band, a process known as VCO band select or autocalibration.

The wide tuning range of the multiband VCOs makes them suitable for use in wideband instrumentation, in which they generate a wide range of frequencies. The 39 bits of fractional-N resolution also makes them ideal candidates for these precise frequency applications.In instruments such as vector network analyzers, ultrafast switching speed is essential. This can be achieved by using a very wide low-pass filter bandwidth, which tunes to final frequency very quickly. The automatic frequency calibration routine can be bypassed in these applications by using a look-up table with the frequency values ​​directly programmed for each frequency, true single core wideband VCOs like the HMC733 can also be used with less complexity.

For phase-locked loop circuits, the bandwidth of the low-pass filter has a direct influence on the settling time of the system.The low-pass filter is the final element in our circuit. If settling time is critical, the loop bandwidth should be increased to the maximum bandwidth permissible for achieving stable lock and meeting phase noise and spurious frequency targets. The narrow-band demands in a communications link mean the optimal bandwidth of the low-pass filter for minimum integrated noise (between 30 kHz to 100 MHz) is about 207 kHz (Figure 20) using the HMC507. This provides approximately –51 dBc of integrated noise and achieves frequency lock to within 1 kHz error in about 51 µs (Figure 22).

By contrast, the wideband HMC586 (covering from 4 GHz to 8 GHz) achieves the optimum rms phase noise with a wider bandwidth closer to 300 kHz bandwidth (Figure 21), achieving –44 dBc of integrated noise. However, it achieves frequency lock to the same specification in less than 27 µs (Figure 23). Correct part selection and the surrounding circuit design are all critical for achieving the best outcome for the application.

Figure 20. Phase noise HMC704 plus HMC507.

Figure 21. Phase noise HMC704 plus HMC586.

Figure 22. Frequency settling: HMC704 plus HMC507.

Figure 23. HMC704 plus HMC586.

Low Jitter Clocking

For high speed digital-to-analog converters (DACs) and high speed analog-to-digital converters (ADCs), a clean low jitter sampling clock is an essential building block. To minimize in band noise a low N value is desired; but to minimize spurious noise, integer N is preferred.Clocking tends to be fixed frequency so the frequencies can be chosen to ensure that the REF _IN frequency is an exact integer multiple of the input frequency. This ensures the lowest in-band PLL noise. The VCO (whether integrated or not) needs to be chosen to ensure that it is sufficiently low noise for the application, paying particular attention to the wideband noise. The low-pass filter then needs to be carefully placed to ensure that the in-band PLL noise will intersect with the VCO noise — this ensures lowest rms jitter.A low-pass filter with phase margin of 60 ° ensures lowest filter peaking, which minimizes jitter. In this manner, low jitter clocking falls in between the clock clean-up application of the first circuit discussed in this article, and the fast switching capability of the last circuit discussed.

For clocking circuits, the rms jitter of the clock is the key performance parameter. This can be estimated using ADIsimPLL or measured with a signal source analyzer. For high performance PLL parts like the ADF5356, a relatively wide low-pass filter bandwidth of 132 kHz, together with an ultralow REF _IN source like a Wenxel OCXO, allows the user to design clocks with rms jitter below 90 fs (Figure 26 ).Manipulating the placement of the PLL loop filter bandwidth (LBW) shows how decreasing it too much has an effect in which VCO noise begins to dominate at small offsets (Figure 24) where the in-band PLL noise would in fact be lower, and increasing it too much means the in-band noise is dominating at offsets where the VCO noise would instead be significantly lower (Figure 25).

Figure 24. LBW = 10 kHz, 331 fs jitter.

Figure 25. LBW = 500 kHz, 111 fs jitter.

Figure 26. LBW = 132 kHz, 83 fs jitter.

Links

Collins, Ian. “Integrated PLLs and VCOs for Wireless Applications.” Radio Electronics , 2010.

Curtin, Mike and Paul O’Brien. “Phase-Locked Loops for High Frequency Receivers and Transmitters.” Analog Dialogue, Vol. 33, 1999.

What does PLL mean? – PLL

definitions

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Major meanings of PLL

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All definitions of PLL

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What does PLL stand for in text

In sum, PLL is an acronym or abbreviation word that is defined in simple language.This page illustrates how PLL is used in messaging and chat forums, in addition to social networks like VK, Instagram, Whatsapp, and Snapchat. From the above table, you can view all PLL meanings: some are educational terms, other medical terms, and even computer terms. If you know of another definition of PLL, please contact us. We will enable it during the next update of our database. Please be aware that some of our abbreviations and their definitions are created by our visitors.Therefore, your suggestion for new abbreviations is welcome! As a return, we have translated the PLL abbreviation into Spanish, French, Chinese, Portuguese, Russian, etc. You can further scroll down and click the language menu to find meanings of PLL in other 42 languages.

SMW Ultra-Low Phase Noise QUATTRO-PLL ± 10 KHz – professional satellite quad-converter Ku-band

• Reception of two polarizations in the full Ku-band;
• Low phase noise fully complies with the Broadcast profile requirements of the DVB-S2 standard.
• ULP – Extra-low phase noise option , ensures compliance with all profiles of the new DVB-S2X;
• High rates of High P1dB and IP3;
• Models with an internal local oscillator (± 5, ± 10 kHz) and stabilization from an external reference generator;
• Wide operating temperature range;
• Compact size and light weight;
• Low gain option;

Attention: The ULP option is implemented during production at the factory by replacing a part of the element base, ordering only together with LNB.

Phase noise Quattro PLL

The phase noise level of the LNB is critical when receiving a phase shift keyed digital signal, i.e. signals with QPSK / 8PSK modulation types in DVB-S2, and multi-position methods of amplitude-phase modulation 16/32/64/128/256-APSK in the new satellite standard DVB-S2X . As the phase shift keying position increases, the LNB phase noise requirements increase. SMW Quattro PLL already in the basic version has phase noise levels (see.specification) that fully comply with the Broadcast profile requirements of the DVB-S2 standard. SMW Quattro PLL with ULP (Ultra Low Phase Noise) option, ensures compliance with all profiles of the new DVB-S2X. Phase noise levels with the ULP option are specified in the specification.

Polarization isolation

The professional converters manufactured by SMW of the PLL Twin and PLL Quattro types include the OMT-Ku orthoplexer, which provides the maximum possible suppression of signals of orthogonal polarizations – from 31.5 dB or more.

The orthoplexer prevents one of the most common satellite reception problems that occurs when there is a transponder close in frequency in opposite (orthogonal) polarization. Inexpensive (household) Twin- and Quadro-converters for collective reception, made according to the scheme “two probes in a round waveguide”, have a typical cross-polarization isolation value of 15 ~ 20 dB, which is not enough to suppress the signal of orthogonal polarization. As a result, the orthogonal signal will reduce the BER at the receive frequency and have the effect of reducing the effective diameter of the receive antenna.

Temperature stability

The parameter of temperature stability of the internal local oscillator (s) of the LNB shows the boundaries of its frequency offset depending on the ambient temperature. For LNBs and BDCs manufactured by SMW, two stability levels are often specified: for the full (-40 to + 80ºC) and typical (-20 to + 70ºC) operating temperature ranges.

The SMW Quattro PLL is available with internal LO stability levels of ± 10 kHz, ± 5 kHz and with an external frequency reference input.

For converters with an external 10 MHz reference frequency input from a reference generator (LNB ext. 10 MHz ref), the temperature stability parameter is irrelevant, since in this case the LNB local oscillator frequencies will not depend on the ambient temperature. Circuits with external input of the reference frequency are used in teleports with a large number of antennas and provide a uniform level of stability of local oscillators of all LNBs, higher than for LNBs with internal local oscillators.

The parameter of temperature stability should be taken into account when choosing a converter for receiving signals with relatively low symbolic flow rates, as well as in the case of a large difference between winter and summer temperatures at the receiving point.

RF quality LNB

Parameters P1dB and IP3 are universal generally accepted parameters of the radio frequency path, showing the quality of its design and the quality of the components used. Swedish Microwave, unlike many other manufacturers, standardizes these parameters in their products and controls their levels during electrical product testing.

Parameter P1dB – 1-dB compression point – reflects the linearity of the LNB RF path.It is the upper limit of the linear section of the amplitude characteristic, the “critical level” of the output power, which should not be exceeded to ensure the specified quality of the device.

Parameter IP3 – 3rd-order intercept point – unambiguously characterizes the linearity and dynamic range of the LNB radio frequency path under conditions of input of many separate frequencies (transponders).