10 most recent topics - The Designer's Guide Community Forum

10 most recent topics - The Designer's Guide Community Forum https://designers-guide.org/forum/YaBB.pl?catselect=measurements - The Designer's Guide Community Forum en-us The Designer's Guide Community Forum Tue, 15 Sep 2026 16:17:10 +0000 http://blogs.law.harvard.edu/tech/rss 30 Other Measurements - Different result with same sample using probe and power supply https://designers-guide.org/forum/YaBB.pl?num=1706775005/0#0 The Designer's Guide Community Forum/Other Measurements https://designers-guide.org/forum/YaBB.pl?num=1706775005/0#0 I tested current force, voltage measure with same sample and probe, tester, but the results (voltage level) were different when compliance level changed. Do you have similar experience or can you give me any advice regarding this? For example, Force [I] || Comp [V] || Measure [V] -100 uA  || -1.5V       ||  -1.5V -100 uA  || -3V          ||  -1.2V RF Measurements - Noise Figure Measurement of 140 GHz LNA using VNA & Power Source https://designers-guide.org/forum/YaBB.pl?num=1693631656/0#0 The Designer's Guide Community Forum/RF Measurements https://designers-guide.org/forum/YaBB.pl?num=1693631656/0#0 Hi, I want to measure the noise figure of 140 GHz CMOS LNA using VNA & power source with probe station. The LNA has 8dB gain and 7.5dB noise figure. Is the measurement error going to be very large due to low gain and high noise figure? I am ok with +/-1dB error. Is there any way to minimise the error? Thanks & Regards Phase Noise and Jitter Measurements - Discrepancy between PSD of matlab script and PSD of Spectre https://designers-guide.org/forum/YaBB.pl?num=1602269884/4#4 The Designer's Guide Community Forum/Phase Noise and Jitter Measurements https://designers-guide.org/forum/YaBB.pl?num=1602269884/4#4 Did you find the jitter value from your Verilog-A / matlab script was matched with the guide (9.8 ps?). Phase Noise and Jitter Measurements - Phase Noise through the NTF of VCO https://designers-guide.org/forum/YaBB.pl?num=1634826957/1#1 The Designer's Guide Community Forum/Phase Noise and Jitter Measurements https://designers-guide.org/forum/YaBB.pl?num=1634826957/1#1 Dear subtr, Do you still have an interest in your question? If so, I can share an Excel workbook that you can use to place your control voltage noise data (noise versus frequency) and it will plot the resulting output phase noise given the Kvco. Shawn Phase Noise and Jitter Measurements - Matching period jitter given in guide https://designers-guide.org/forum/YaBB.pl?num=1673629408/0#0 The Designer's Guide Community Forum/Phase Noise and Jitter Measurements https://designers-guide.org/forum/YaBB.pl?num=1673629408/0#0 Hello, I read the guide Modeling Jitter in PLL-based Frequency Synthesizers by Ken Kundert. I am trying to match the jitter reported in this guide (9.8ps), but the output of the matlab script is giving 11.1 ps jitter. I also hard-coded the tt values but this didn't seem to help either. I have copied Listing 6 - 8 and placed into Virtuoso running spectre and checked the parameters given in the netlist. Attached is my netlist from Spectre. Code:<pre class="code" style="margin: 0px; width: 90%; height: 300px; overflow: auto;">// Design library name: PLL_VA // Design cell name: pll_jitter_678 // Design view name: schematic simulator lang=spectre global 0 // Library name: PLL_VA // Cell name: pll_jitter_678 // View name: schematic I0 (REF) osc6 freq=25M ratio=125 Vlo=-1 Vhi=1 tt=((0.01)*(125))/(25E+6) \ accJitter=14e-12 syncJitter=2e-9 I1 (VCTL REF FB) pfd_cp7 Iout=500e-6 dir=1 tt=1e-09 ttol=1e-12 I2 (FB VCTL) vco8 Vmin=-4 Vmax=4 Fmin=1e+9 Fmax=3e+9 ratio=10000 Vlo=-1 \ Vhi=1 tt=((0.01)*(10000))/(3e+9) jitter=4.5e-12 \ ttol=((1e-06)*(10000))/(3e+9) outStart=10e-3 C1 (net1 0) capacitor c=625p C0 (VCTL net1) capacitor c=3.125n R0 (net1 0) resistor r=10K isnoisy=no simulatorOptions options psfversion="1.4.0" reltol=1e-3 vabstol=1e-6 \ iabstol=1e-12 temp=27 tnom=27 scalem=1.0 scale=1.0 gmin=1e-12 rforce=1 \ maxnotes=5 maxwarns=5 digits=5 cols=80 pivrel=1e-3 \ sensfile="../psf/sens.output" checklimitdest=psf tran tran stop=60m skipdc=yes write="spectre.ic" writefinal="spectre.fc" \ annotate=status maxiters=5 finalTimeOP info what=oppoint where=rawfile modelParameter info what=models where=rawfile element info what=inst where=rawfile outputParameter info what=output where=rawfile designParamVals info what=parameters where=rawfile primitives info what=primitives where=rawfile subckts info what=subckts where=rawfile saveOptions options save=allpub </pre> In Matlab, I am using the periods.m file and using the mapping to VCO jitter by dividing by sqrt(N). Code:<pre class="code" style="margin: 0px; width: 90%; overflow: auto;">load periods.m; % output estimates of period and jitter N = 10000; %Frequency division T=mean(periods); J=std(periods); Jvco = J/sqrt(N); </pre> Did I miss something? It would give me more confidence if my result matched the guide before modifying further. RF Measurements - How to characterize effective capacitances of Mosfet and FinFet? https://designers-guide.org/forum/YaBB.pl?num=1628540165/1#1 The Designer's Guide Community Forum/RF Measurements https://designers-guide.org/forum/YaBB.pl?num=1628540165/1#1 You need to develop or use a device model, and define all the parameters you are interested in. Once you have these, the creation of the testbench and setting up the post-processing functions will be a straightforward, though potentially laborious exercise. Phase Noise and Jitter Measurements - VCO Phase Noise Modeling using Verilog-A, Verilog-AMS https://designers-guide.org/forum/YaBB.pl?num=1582082899/2#2 The Designer's Guide Community Forum/Phase Noise and Jitter Measurements https://designers-guide.org/forum/YaBB.pl?num=1582082899/2#2 If you can assume the noise is dominated by white noise, then you can actually make the vco model in verilogAMS by deriving period jitter from it. Now given that the noise at an offset is known, the curve is completely defined in all the points or in other words you can find out the N=H(f) of the noise. Assuming that you need the period jitter, multiply it by a (1-zinv) filter and integrate the noise. This is the sigma of each period. Now you find a random number in your code based on this sigma and pass it to the oscillator. It will generate an integrated noise which corresponds to the PSD of your actual oscillator. Da Dalt's book on understanding jitter has details on retrieving period jitter from spot noise of purely 1/f^2 noise. You can even model flicker noise by using multirate filters to create 10dB/decade which is explained in Staszewski's book. But it can be a next step. Phase Noise and Jitter Measurements - Simulation to retrieve reference spur https://designers-guide.org/forum/YaBB.pl?num=1620755917/0#0 The Designer's Guide Community Forum/Phase Noise and Jitter Measurements https://designers-guide.org/forum/YaBB.pl?num=1620755917/0#0 Hi, Regarding how to calculate the reference spur analytically is available everywhere. Could anyone suggest a methodology for simulating and measuring the reference spur for a charge Pump that has a pre determined static phase offset. Assume the LF to be the standard C1, R, C2 type. Phase Noise and Jitter Measurements - (Multi-modulus) divider phase noise simulation https://designers-guide.org/forum/YaBB.pl?num=1603971413/0#0 The Designer's Guide Community Forum/Phase Noise and Jitter Measurements https://designers-guide.org/forum/YaBB.pl?num=1603971413/0#0 Hello everyone, Sorry if I missed the topic and the question is already answered. I want to simulate the phase noise contribution of an MMD used in a frequency synthesizer. For the purpose of simulation, the division is integer ( divide by N ). I use PSS and add Beat frequency to be Fvco/N ( where Fvco is the vco output frequency ). Also i add harmonics to be 5*N ( that would equal to 5 harmonics of Fvco). Then in Pnoise simulation , I use 10 maximum sidebands and add the voltage nodes I am interested in ( output nodes of MMD ). Im measuring relative harmonic 1 also. Is this the correct way to simulate a divider or am I missing something? Thank you in advance Phase Noise and Jitter Measurements - Phase Noise of Squared Noisy Sine Wave (Ian Galton's Paper) https://designers-guide.org/forum/YaBB.pl?num=1603949787/0#0 The Designer's Guide Community Forum/Phase Noise and Jitter Measurements https://designers-guide.org/forum/YaBB.pl?num=1603949787/0#0 I have read [I. Galton 2018] and wanted to understand the effect of squaring deeply. I made a simple experiment to observe the effect of squaring, but I am unable to make sense of the results. MATLAB experiment description: I have taken a sine wave of frequency 100MHz, sampled at the rate 100GHz. To this sine wave, I have added a sinusoidal phase noise of magnitude "alpha" and frequency 10MHz. When I take the FFT of the resultant signal, I get the expected frequency spectrum. Code:<pre class="code" style="margin: 0px; width: 90%; overflow: auto;">clear all close all; f0 = 100e6; df = 10e6; tTotal= 1e-6; Fs = 100e9; Ts = 1/Fs; t = 0:Ts:tTotal-Ts; alpha = 1e-6; a = sin(2*pi*f0*t + alpha*sin(2*pi*df*t)) ; afft = fft(a)/length(a); afftdb = 20*log10(abs(afft)+1e-8); figure(1) plot(afftdb); </pre> <img src="https://i.stack.imgur.com/dHyUpm.png" alt="" border="0" /> The strength of the spur at bin 111 is 20log(alpha/2) relative to the carrier as expected. Next, I have converted this sine wave into a squarewave, then hann-windowed, then low pass filtered and finally I've taken the FFT. Code:<pre class="code" style="margin: 0px; width: 90%; overflow: auto;">asquare = sign(a); y = lowpass(asquare,200e6,Fs,'ImpulseResponse','iir','Steepness',0.95); win = 0.5*(1-cos(2*pi*t/tTotal)); y =y.*win; %asq_fft = fft(asquare)/length(a); asq_fft = fft(y)/length(a); asq_fftdB = 20*log10(abs(asq_fft)+1e-8); figure(2) plot(asq_fftdB) </pre> I get spur of strength -64dB which is unexpected for me (see below image). I didn't expect to get this high spur. I expected the spur to still be 20log(alpha/2) relative to the carrier. I also don't understand why I get so many harmonics too. <img src="https://i.stack.imgur.com/geiK9m.jpg" alt="" border="0" /> I also tried changing the value of alpha from 1e-6 to 1e-11. The FFT plot for alpha of 1e-11 is given below: <img src="https://i.stack.imgur.com/geiK9m.jpg" alt="" border="0" /> Still, the strength of the spur didn't change. This is surprising to me. Could anyone please explain why does the spur's strength of -64dB make sense? When I make alpha = 0, there are no spurs. So, there is no FFT leakage issue here. [I. Galton 2018] I. Galton and C. Weltin-Wu, "Understanding Phase Error and Jitter: Definitions, Implications, Simulations, and Measurement," in IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 66, no. 1, pp. 1-19, Jan. 2019, doi: 10.1109/TCSI.2018.2856247.