Phase locked loop pll is a technique which has contributed significantly toward the technology advancement in communication and motor servo control systems in the past 30 years. The most versatile application of the phase locked loops pll is for clock generation and clock recovery in microprocessor, networking, communication systems, and frequency synthesizers. This synchronisation stage is usually based on a phase locked loop pll 3. Phase comparator i is an exclusiveor network that operates analogously to an overdriven balanced mixer. Introduction to phase lock techniques introduction objective. Mixedsignal ics combine both analogue and digital circuitry. The phase locked loop 14 is a useful control systems tool used heavily in communications engineering, radar, sonar, control engineering and many other applications. Introduction to phase locked loop system modeling introduction phase locked loops plls are one of the basic building blocks in modern electronic systems. Fpgabased digital phase locked loop analysis and implementation by dan hu thesis submitted in partial fulfillment of the requirements for the degree of master of science in electrical and computer engineering in the graduate college of the university of illinois at urbanachampaign, 2011 urbana, illinois advisers. The performance of the motor speed control required in. Combining this with the digital integrator of the dco. Introduction there has been an increase in the integration of renewable energy sources into the electricity grid. Ims are used in many industry sectors as the leading element to convert electrical energy into mechanical one.
The baseband model of analog phase locked loop and its linear theory were discussed on the lecture. Phaselocked loop design fundamentals application note, rev. Perrott 2 why are digital phaselocked loops interesting. Presentation outline what is phase locked loop pll basic pll system problem of lock acquisition phase frequency detector pfd charge pump pll application of pll 3. A phaselocked loop is a feedback system combining a voltage controlled oscillator vco and a phase comparator so connected that the oscillator maintains a constant phase angle relative to a reference signal. What is phase locked loop pll pll is an electronic module circuit that locks the phase of the output to the input. This ocw supplemental resource provides material from outside the official mit curriculum. This phase locked loop keeps the generated signal and reference signal in a fixed relationship. In all pll applications, the phase locked condition must be achieved and maintained. Highspeed lowpower phaselocked loops plls are an integral part of frequency synthesizers and clock recovery circuits.
Introduction to phaselocked loop system modeling introduction phase locked loops plls are one of the basic building blocks in modern electronic systems. A software phaselocked loop from theory to practice. An46 the phase locked loop ic as a communication system. Phase locked loop is one of the most commonly used circuit in both telecommunication and measurement engineering. Phase locked loops an overview sciencedirect topics. A lowpower adaptivebandwidth pll and clock buffer with supplynoise compensation, ieee. Fundamentals of phase locked loops plls fundamental phase locked loop architecture. National aeronautics and space administration technical report no. Since the advancement in the field of integrated circuits, pll has become one of the main building blocks in.
A pll is a negative feedback system where an oscillatorgenerated signal is phase and frequency locked to a reference signal. First time, every time practical tips for phase locked loop. A phase locked loop is a clever piece of analog and digital circuitry that can be used, among other things, to multiply by an integer number the frequency of a signal. But the technology was not developed as it now, the cost factor for developing this technology was very high. They can be configured as frequency multipliers, demodulators, tracking generators or clock recovery circuits. Short course on phaselocked loops and their applications. The phase locked loop ic as a communication system building block an46 national semiconductor application note 46 thomas b. A typical pll application loop filter phase detector f in t f out t f feedbackt voltage controlled oscillator vco from a pll system point of view, the dco has the same function as the vco, but it is implemented in the digital domain, so the output frequency of the dco is a function of the input digital value. Introduction the phase locked loop 14 is a useful control systems tool used heavily in communications engineering, radar, sonar, control engineering and many other applications. The analog and digital signals are used in the phase locked loop. In communications plls are used for carrier tracking, frequency synchronization, phase synchronization and symbol timing synchronization. The range of input frequencies between the value at which the loop is locked with a phase difference of 0 and 180 is called the loops lock range. Phaselocked loops can be used, for example, to generate stable output high frequency signals from a fixed lowfrequency signal. Index termsalldigital phaselocked loop pll, bilinear transform, digital loop filter, digitally controlled oscillator.
Only the analog phaselocked loop apll is discussed in this course. Introduction 11 carrier recovery 2 12 clock recovery 3 tracking filter 3 14 frequency demodulation 4 15 phase demodulation 5 16 phase modulation 5 17 frequency synthesis 6 18 organization of text 7 19 other information on phase locked loops phase locked loop basics 21 phase locked loop characteristics 9. Inventions in pll schemes combining with novel imte. Abstract phaselocked loop pll is a technique which has. It consists of four flipflops, control gating and a 3state output ci rcuit comprising p and ntype drivers with a common output node. They also lock the output phase to the input phase, as you would expect from the name phaselocked loop, but its a different sort of lock. In view of its usefulness, the phase locked loop or pll is found in many wireless, radio, and general electronic items from mobile phones to broadcast radios, televisions to wifi routers, walkie talkie radios to professional communications systems and vey much more. Depending on the operation principle of loop components we distinguish analog digital hybrid phaselocked loops. In this article different types of phased locked loop technique are studied and after comparing all circuits we found that the digital phased locked loop have result in good phase noise. Phaselocked loops plls have been around for many years1, 2. Nov 03, 2016 phase locked loops are used in many radio frequency of rf systems. Phase locked loops pll introduction to pll the concept of phase locked loops pll first emerged in the early 1930s. Lecture 050 linear phase lock loops i 51403 page 05021. Phase locked loop design fundamentals introduction the purpose of this application note is to provide the electronic system designer with the necessary tools to design and evaluate phase locked loops pll configured with integrated circuits.
A software phase locked loop from theory to practice. This comprises a servo loop, where the vco is phaselocked to the input signal. Phase locked loops, block diagram,working,operation,design. This comprises a servo loop, where the vco is phase locked to the input signal. Introduction phase lock loops plls have been one of the basic building blocks in modern electronic systems.
A phaselocked loop or phase lock loop is a control system that generates an output signal whose phase is related to the phase of an input signal. This is the frequency range around the free running frequency that the loop can track. Phaselocked loop is one of the most commonly used circuit in both telecommunication and measurement engineering. They have been widely used in communications, multimedia and many other applications. This frequency is divided by r to a lower frequency, which is called the comparison frequency. The pll phased locked loop starts with a stable crystal reference frequency. Design ofmonolithic phaselockedloops and clock recovery circuitsatutorial behzad razavi abstractthis paper describes the principles of phaselocked system design withemphasis on monolithic imple mentations. Apr 03, 20 what is phase locked loop pll pll is an electronic module circuit that locks the phase of the output to the input. Performance is important phase noise can limit wireless transceiver performancejitter can be a problem for digital processors the standard analog pll implementation is problematic in many applicationsanalog building blocks on a mostly digital chip pose design and verification challenges. Razavi, design of analog cmos integrated circuits, chap. Applications of phase locked loops play an increasingly important role in modern electronic systems, and the last 25 years have seen new developments in the underlying theories as well. The report will describe through simulations, every aspect of the implementation of a pll in software which in hardware would be through a digital signal. A versatile and useful introduction to phase locked loops. Phase detector 1 is used in applications that require zero frequency and phase difference at lock.
Phase locked loops plls are commonly used to generate welltimed onchip clocks in highperformance digital systems. Only the analog phase locked loop apll is discussed in this course. Depending on the operation principle of loop components we distinguish analog digital hybrid phase locked loops. Presentation outline what is phase locked loop pll basic pll system problem of lock acquisition phase frequency detector pfd. The objective of the feedback loop, the pll, is to keep. Phaselocked loop phase comparator 2 is an edgecontrolled digital memory network.
Theory and practica design of phase locked receivers. The root locus for a typical loop transfer function is found as follows. The phase locked loop detector compares the input frequency and the output frequency of the vco to produces a dc voltage which is directly proportional to the phase distinction of the two frequencies. The concept of phase locked loops pll first emerged in the early 1930s. The loop is no longer locked and the input and vco frequencies are no longer the same. Phase locked loop operating principle and applications. A 7 v regulator zener diode is provided for supply voltage regulation if necessary. The lock range above and figure 3 the 565 integrated circuit pll contains almost all of the. It is the most important part of the phase locked loop system. The hef4046b is a phaselocked loop circuit that consists of a linear voltage controlled oscillator vco and two different phase comparators with a common signal input amplifier and a common comparator input. Feb 10, 2012 blog post for more info schematic, etc. Anything using radio waves, from simple radios and cell phones to sophisticated military communications gear uses plls. A digital phase locked loop speed control of three phase. The data clock is generated by using a phase locked loop pll as a fre.
In recent development era of new involvement of emerging. The phase locked loop or pll is a particularly useful circuit block that is widely used in radio frequency or wireless applications. The oscillator generates a periodic signal, and the phase detector compares the phase of that signal with. Design ofmonolithic phaselockedloops and clock recovery. Perrott on analog and digital phase locked loops and their applications. Tim wilmshurst, in designing embedded systems with pic microcontrollers second edition, 2010. The majority of all pll design problems can be approached using the laplace transform technique. First time, every time practical tips for phaselocked loop design. Smallsignal modelling and stability assessment of phase. A phase locked loop is a feedback system combining a voltage controlled oscillator vco and a phase comparator so connected that the oscillator maintains a constant phase angle relative to a reference signal.
Introduction and history of the phase locked loop 2 references for chapter 1 3. The theory and mathematical models used to describe plls are of two types. Introduction we will analyze the pll in terms of phase. Jun 20, 2003 phase locked loops plls are electronic circuits used for frequency control. Introduction to phase locked loop pll digitavid, inc. The figure shows the block diagram of the phase locked loop system in fm transmitter that consists of different blocks such as a crystal oscillator, phase detector, loop filter, voltage controlled oscillator vco, and frequency divider. Phase detector 2, if quadrature lock is desired, when detector 1 is used in the main loop, detector can also be used to indicate whether the main loop is in lock or out of lock. Gardners short history links the earliest widespread use of plls to the horizontal and vertical. A versatile building block for micropower digital and analog applications. The communications industrys big move into wireless in the past two years has made this mature topic red hot again. Most of the answers can be found in the lecture notes. Pll, phase frequency detector, charge pump, low phase noise, low jitter.
The locking action is made possible by negative feedback, i. It is possible to have a phase offset between input and output, but when locked, the frequencies must exactly track. Phase locked loop design fundamentals application note, rev. A multiband phaselocked loop frequency synthesizer. L lock range where kv ko kd, the product of the phase detector and vco gains. The main challenge is based on robustness and low cost. Phase locked loops presents the latest information on the basic theory and applications of plls. The objective of this thesis is to present an introduction to the theoretical. The fft of the multiplier signal s3 consists of two pulses, one at dc since the phase difference is not a function of the frequency and the second at twice the. Pdf in this article different types of phased locked loop technique are studied and after. Lecture 050 linear phase lock loops i 51403 page 0501. Mills june 1971 the phase locked loop ic as a communication system building block introduction the phase locked loop has been found to be a useful element in many types of communication systems. A phase locked loop or phase lock loop pll is a control system that generates an output signal whose phase is related to the phase of an input signal. Phase locked loops plls have been around for many years1, 2.
A design procedure for alldigital phaselocked loops based on a. Topics include vcos, loop filters, phase detectors, timetodigital converters, vcobased analogtodigital converters. Iyer 1 abstract any grid connected inverter requires accurate information of the phase angle and frequency of the grid through a phase locked loop pll. When the pty pe or ntype drivers are on, they pull the output up to. The conventional and simplest pll design process assumes a simple pll small signal model and. Understand the principles and applications of phase locked loops using integrated circuit technology with emphasis on cmos technology. Phase locked loops have many different applications and come to communications systems. Introduction to phase lock loop system modeling by wen li, senior system engineer, advanced analog product group and jason meiners, design manager, mixedsignal product group, texas instruments incorporated 1. In order to avoid distortion, many applications require operation in the linear region, that is, the total variance of the phase. To understand the working of the phase locked loop system, let us consider the fm transmitter, which can be considered as one of the most frequently used pll applications pll circuit in fm transmitter is a closed loop feedback control system. Introduction to phaselock loop system modeling by wen li, senior system engineer, advanced analog product group and jason meiners, design manager, mixedsignal product group, texas instruments incorporated 1. First time, every time practical tips for phase locked. The multiband pll frequency synthesizer uses a switched tuning voltage.
A pll is a feedback system that includes a vco, phase detector, and low pass filter within its loop. A phaselocked loop is a feedback system combining a voltage controlled oscillator vco and a phase comparator so connected that the oscillator maintains a. Basic principles, phase detector, vco, low pass filter. The pll is a control system allowing one oscillator to track with another. The negative feedback loop forces the plls output signal to be phase locked with the input signals. Note that its average amplitude is 0 and it seems to be of higher frequency than the original signals s1 and s2.
1165 916 489 1055 656 1091 624 178 243 856 537 411 1507 129 1184 1460 1511 1562 1118 570 286 187 785 1024 254 595 855 749 757 597 454 1292 703 673 446 1483