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54 Threads found on Phase Error Pll
This question is not pertaining to any datasheet but philosophy of pll. I was referring to the link . I found the following statement "When the pll, phase locked loop, is in lock a steady state error voltage is produced. By using an ampli
I presume you "no voltage is applied" means no input to the pll phase detector rather than "no voltage applied to the VCO". Secondly, VCO input isn't generally zero in locked state, it's the voltage required to set the locked frequency. It should be noted that your schematic isn't very detailed. There's usually an integrator (often implemented
In the linear tracking mode, you can frequency modulate the signal with a sine wave and measure the loop response to determine the -3dB point. Loop gain and obviously the VCO gain and range in particular influences the -3dB bandwidth set by just the LPF's but since phase error is limited and non-linear beyond the type II range, this will also aff
Open loop frequency error is a phase shift integral over time. Closed loop with phase detector and adequate bandwidth, uses negative feedback and phase detector as integrator to null the phase error.
There is a non-linear effect of Loop BW on Capture range and lock-in time. THe error signal in f must be within the loop bandwidth. Using CMOS analog switches , one can change the bandwidth after locked as long as an offset is not induced or a large transient pF pulse discharge. Or one can use a linear AGC approach to change bandwidth smoothly.
The demodulation is done with a pll, but detection of phase error and frequency is determined by stability of frequency, modulation rate , SNR, BER, cost all affect choices in design solutions. ideal "matched receiver" might look like the synch
This requirement is actually similar to the Type II phase comparator in the old CD4046B pll except it goes high when one leads the other and low when it lags then becomes tri-state floating when in sync. The output pulse width is thus a current pulse that can be integrated with a cap load to measure the phase error and for (...)
What f is driving the coils? What BW is filter and sample rate f? - - - Updated - - - Some pll may be necessary but you are measuring ~DC magnetic field. Good "Mags" have 50-100Hz BW. - - - Updated - - - I recall for measuring small magnetic field changes at 100k and 200
1553 modulation is Biphase , so clock recovery to 0.1% long term is normal, short term depends on Noise and method used, pll or 1-shot at 3/4T i have no idea why they specify freq error on Biphase , when for Rx, only phase noise and phase margin counts.
The purpose of Gain in pll is to analyze Loop gain stability under different conditions. a phase detector has a transfer function of k/s, like an integrator, since the integral of frequency is phase and the output , k will be in terms of volts per cycle of phase error. Thus k is usually the mixer voltage (...)
Hi, I'm a student and I am trying to demonstrate pll by modeling it on SIMULINK. But I couldn't find phase detector component in simulink libraries. As I have noted in several threads, I tried to use a "mixer" instead of a PD. But still I couldn't get the desired output. Please see the simulink model I have attached below and please let me know if
If there is a "fixed frequency offset" in your pll, then one of the following is happening: 1) the pll is not actually phase locked 2) you are programming the bits incorrectly 3) you are saying there is a "fixed offset" based on a poor (inaccurate) frequency counter reading You should figure out which it is.
The pll has a loop bandwidth. If you are inside of +/- the loop bandwidth from the VCO carrier, then the phase noise of the output is no better than 20 Log N + Reference phase noise. i.e. the reference phase noise as degraded by the pll. If you are outside of the loop bandwidth, the (...)
In a phase-modulation scheme,rms phase error is very critical,it should be less than 2deg in most cases. This rms phase error directly relates to in-loop phase noise of pll output. while working with pll frequency synthesizer, we come across two (...)
An internal charge pump with a cap is equivalent to an external integrator with a reference voltage equal to no phase error. When the phase error is a pulse controlled current source going into capacitive load , they call it a charge pump or essentially an integrator. This is an essential part of the pll (...)
formulae as I recall from the late 70's for Loop filter get complicated for capture range , phase noise reduction of clock or stability . Modelling is required by trial and error as there is a trade-off between desired capture time and jitter reduction as well as capture range and clock error. You need to define these parameters before you (...)
If you put the two outputs to a mixer you will get a DC and a 2X output. Filter for the DC, and do a calibration of DC voltage vs phase error using some fixed delay -> static phase -> DC voltage points.
If there is a dead zone, then there can in-fact be a phase error. I would think of it more as a phase noise term, rather than an error, since the VCO will be moving around slightly due to random noise. If you can stand slightly higher clock spurs, you can apply a bias so that the phase detector stays out of (...)
Hi, I am using pll block in simulink for detecting frequency of a 2 kHz signal. I don't know how to adjust gains in order to have minimum rise time, and minimum error. I tried the recommended setting by simulink first, but it didn't work. thanks, Elham
hey guys this is my first time to post question here... I need to design a pll by using matlab, but what my professor lectures in class is very confusing. Here's my matlab code and also attached: e = zeros(1,1000); % Initializing the error signal wc = 2*pi*95/800; % Omega for the signal coming out from VCO % with init
Precisely. A phase detector, in general, is designed to put out "zero error volts" when the measured signal is locked to the reference signal. The details vary widely in phase detector and loop filter types. But assume the phase detctor has a single output "DC" voltage. When the signals are locked in (...)
Is it possible to determine the phase error of a pll in steady state knowing only: - open loop dc gain value (kv) - vco gain (kd) - the phase detector is a 4 quadrant multiplier
I need to do a simulation aboat pll in simulink,but I am a layman in the filed. Anyone who know something in the field must give some tips. 1 I download a package from but the files cannot be implemented,there are always some error.If some one who know why ,plea
Hi All I have designed a pll at 60Hz to lock onto AC mains for a solar inverter. I am using a first order filter and I am not able to achieve the phase margin. I have used a higher order filter but things do not work. What else can I do to improve my phase. I can only afford 2degree phase error between my (...)
hi all In a pll LPF filter, I am not able to achieve the required phase margin. I am using a second order passive filter. How can I improve my phase error. I can afford a max of 2 degrees but it is more than 30 degrees phase error? Please reply
hi all I am working on a pll. The maximum phase error that I can afford between my input and output is 2 degrees. The pll lock range is 47Hz to 63Hz with a reference of 60Hz grid 3v peak to peak. VCO center frequency is 55Hz ...I am having too much phase lag...what is needed to reduce it....I am using a 2nd (...)
pll phase error RMS = 107 x √ Loop_Bw x 10^(phase_Noise / 20)
Are you talking about a little phase error offset that is constant, or a big phase error that moves around if you breath on the circuit. In the later case, you should suspect that the pll is not truly locked. In the former case, yes, there is a small static phase error (...)
A pll is a control loop. It senses the phase of the VCO, and compares it to some reference. If there is a phase error, it "tunes" the VCO either up or down to minimize the phase error. A number of factors influence how quickly it corrects a phase error, (...)
Apply a sine wave at the frequency of pll BW of specified amplitude on the VCO supply. Plot the variation in frequency. This will be of the same period as the supply disturbance, but with a phase delay. Integrate one half of the period of this waveform (excess frequency) to get the phase error. Convert this (...)
Don't know. Are you talking real-world or simulated by someone's software? 2nd order loop settles until there is a zero phase error. A 1st order loop will settle to a fixed error phase. Maybe that is the difference--a different end point?
Graphs seems reasonable. Freq goes up to 2.4GHz in 60 us, the freq error is simply the difference between your target freq and your actual freq, phase error goes to zero in 100us. I hope this can help. Mazz
hi, i want to know how the inetrpolater,phase detector and loop filter works in digital timing the phase detector gives the error signal with 2 samples using gardner it know the exact sampling the loop filter give the mue i.e fractional delay n system clock as output with input as (...)
There are probably several ways. Maybe a pll where you sample and compare the input and output signal and use the error signal to drive a phase shifter. You didn't mention if this was CW or a modulated signal.
V_e =out put voltage of phase detector(P.D.)θ_e=output pahe o PD.K_a=gain of amplifier.K_o=gain of vco & k_V=k_a×K_o×K_d & k_d =gain of PD
They probably use an integrated charge pump to integrate the error signal of the phase detector. Since an integrator has a LP behaviour, choosing the right integrating constant (C/gm) results in a stable loop.
A DLL is a delay locked loop. Rather than adjust the phase until the error is zero, the output signal is delay with a tapped delay line and the taps are adjusted until the delay error is minimal. Zero error cannot usually be obtained because of the coarseness of the delay steps. On some DLL systems, the output jitter is (...)
Assuming there is no other nonideal effect except the current mismatch in charge pump,is there phase error when pll is locked?if there is,the phase error is fixed or changing?and why?thanks a lot
Hi fanshuo, Are you sure that adding the second pole you did not decrease the dc gain of the loop? How do you measure the steady state phase error? Regards Z
the static pase error always be in the type 1 pll , where there is one integrtor in the loop which is the VCO this can be used by using 2nd order pll , this will eleminate the static phase offset
It it the relation between the average of UP-DN signals Vs the the input phase error. It can be plotted by running multiple transient simulations , each time you change the delay between the input clocks. each transient simulation shall be left for a long enough time , in order to get an acurate average. Also The PFD has another C/Cs which is
Hello, I have a question.Static phase error spec makes sense only in the pll locked condition i.e CP output voltage in locked condition or should it be checked @ 0 and Max CP output voltage?Please comment in this regard... Regards, Ashish.
the linear model if build for lock or near lock state , to give a simple formulas , abut how the pll will act , but sure for the unlock or far from lock u need to model the pll not in S domain , this also will show how the pll will act , in the beginning of acquisition phase khouly
hi all, i want to know what will happen to pll's performance when input reference clock is high about 100-500MHz. for example, as i observed, when the input clock is about 200MHz, the static phase error is very small, less than 10ps. and some other the bad effects such as leakage currents, mismatch in charge pump currents, can be smaller (...)
Poor phase error usually indicates problems with I/Q modulators, pll performance, group delay in filters, or amplifiers in the transmitter circuitry.
I have a pll transient simulation. When pll is very likely locked,i.e.,loop filter voltage has less than 1mV ripple and after >10us settling. But look at the charge pump up/down current pulse I found there is a constant phase error(about the same big as the PFD delay chain's delay time) between the Fref and Fdiv. My (...)
what is the max phase error of a fractional pll? ex: a pll with a mash 111 delta-sigma modulator. the divider has 8 output level: 10,11,12,... 17. pll reference clk is 10MHz. What will be the maximum phase error between the PFD input(ref and div_out)? thanks.
Actually if we use a phase detector in the pll, then we use LPF only to cut the transients that comes out from the detector along with a DC voltage that denotes the phase error.Because only when the control voltage to the VCO is stable, it can work properly. If we make use of a Frequency detector instead of (...)
Hi guys can you please help me i am simulating an fm system here is the code below I am having a problem on the demodulation side I am trying to demodulate using pll desgning (phase Lock Loop). But it is giving me an error at last line R has to be positive number I think its R please help I am giving up = mp3read('jem.mp3'); s
Today most important topic is phase noise of the closed loop pll. That is because nearly all new developed system specs use higher order symbol constellations (64QAM) and have wideband RX channel (>10MHz). So the error vector magnitude of the phase noise integrated over the RX bandwidth is the most important. If you minimze (...)