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Plot Oscillation frequency vs Time in Cadence?

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abe_00

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I want plot oscillation frequency vs time in cadence ,but i don't have the use "freq" function in calculator ?
I only have "frequency" function.
my cadence 5.10.41.168
can anyone help ?
 

dick_freebird

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I once made a veriloga widget that watched for zero crossings,
took t(N)-t(N-1) and output a 1/t=frequency image voltage.
This being a real-time frequency measure, for a single tone
system at least.
 

abe_00

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Surely search "freq()".

If you can't find it, see usage of it by "skill finder".
Or enter "ocnHelp 'freq" in CIW.
I can't find "freq()"
When i enter "ocnHelp 'freq"
CIW Info : No help is available for : "freq".

Does they have some problem in my license??

thank you!
 

abe_00

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1.jpg

:-x:-x:-x:-x:-x:-x:-x:-x:-x:-x:-x:-x:-x:-x
 

pancho_hideboo

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It seems that occHelp is not provided for "freq()".
Use "skill finder".

If you can't find out "freq()" even in "skill finder", I can show you alternative skill code for "freq()".

Code of "freq()" is very easy.
 

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abe_00

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Maybe my cadence can't support the "freq" function . I can't find out "freq()" in "skill finder".

I download IC5141 USR6 , I find out the function in "skill finder".

thank you ..
 

hesam_ahmadi

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user frequency() instead freq.
you can see help using: ocnHelp 'frequency

i know this is a late answer but i may helpful for other
 

Teddy

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I don't believe your version of cadence supports the frequency over time. You will have to work around it which is not easy.
What you can do (but it will not be very fast) is to use function frequency() and clip. This way you can find frequency of first 2 pulses and then clip the waveform so you move in time and run it as a cyscle. For this you can use ocean script.
Not very easy though. Or you can try to use the verilogA thingy attached (compile it and make and put the symbol to your schematic) - it has precission issues like all VerilogA stuff.
 

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aryajur

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Once I had to plot the duty cycle wrt time. I just used a filter to get the voltage as the indication of the duty cycle and that did the job satisfactorily for me. For getting the frequency you can create a differentiator using Cadence's analogLib ideal components cap, vcvs, res, etc. and then add a filter to get a voltage proportional to the frequency in time. But this would only work if your time scale is very large and your frequency range is high to be satisfactorily seen. If not then you may have to revert to ocean and do some wave processing in code as suggested above. If you are not comfortable with Ocean, even doing it in MATLAB or something similar is another option.
 

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