PSS simulation

 Hi Andrew,

Thanks for your reply.  The clock is not doing the sampling. Clock is 1.2GHz and clocks a logic which based on it and on an asynchronous input  generates a signal, periodic in its nature, which then clocks the switches in the SC core.So, in short, the sampling signal is periodic and "kind of" synchronized to the clock but only kind of because of the asynchronous signal. The sampling signal is 27.918MHz while the clock is 1.2GHz.

It is a bit unclear what you wrote in 1). Where do I find  pwlperiod and pwlperiodstart  ? 

A side question: which document in the cadence documentation describes the settings and GUI for pss, pac and pnoise? What I have read is just Ken Kundert's paper on simulating SC circuits.

My 1.2GHz voltage source is defines as pwlf source and basically is a clock with a period of 833ps and starts from 0 and ends at about 198ns.

The analysis statements are :

simulatorOptions options reltol=1e-3 vabstol=1e-6 iabstol=1e-12 temp=65.0 \
    tnom=27 scalem=1.0 gmin=1e-12 rforce=1 maxnotes=5 maxwarns=5 digits=5 \
    cols=80 pivrel=1e-3 sensfile="../psf/sens.output" checklimitdest=psf
pss  pss  fund=27.918e6  harms=0  errpreset=moderate  tstab=72.2194n
+    \
    swapfile="/lsi/dv/analogsim/svilen/spyder/test_Pnoise/spectre/schematic/distributed/Pnoise/swap"
+    maxacfreq=2.8e9  annotate=status
pnoise  (  dac_diff  gnda  )  pnoise  start=10  stop=13.959e6
+       dec=100  maxsideband=100  noisetype=timedomain  numberofpoints=0
+       noisetimepoints=[35n]  annotate=status

The PSS starts like this:

=================================
`pss': time = (0 s -> 219.661 ns)
=================================
Important parameter values in tstab integration:
    start = 0 s
    outputstart = 0 s
    stop = 219.661 ns
    period = 35.8192 ns
    step = 219.661 ps
    maxstep = 1.43277 ns
    ic = all
    skipdc = no
    reltol = 1e-03
    abstol(V) = 1 uV
    abstol(I) = 1 pA
    temp = 65 C
    tnom = 27 C
    tempeffects = all
    method = traponly
    lteratio = 0
    relref = sigglobal
    cmin = 0 F
    gmin = 1 pS

And the PNOISE analysis starts like:

**************************************************************
Periodic Noise Analysis `pnoise': freq = (10 Hz -> 13.959 MHz)
**************************************************************
Using the operating-point information generated by PSS analysis `pss'.
Working on time-domain noise timepoint 1 of 1 (time=218.841 ns).

Why is it working on timepoint 218.841ns when I have asked it to calculate the noise at 35ns?

Thanks again

How to set the stop time of PSS simulation sir? I am a foolish student as can easily be obtained from my user alias. : )

JackieTheBanan said:

I am a foolish student as can easily be obtained from my user alias. : )

This is the best post I've seen on the forums - it made me laugh out loud (much to the amusement of my colleagues)!

LOL!  I'm right there with Andrew.  You definitely win the prize for Best Post Ever, JackieTheBanan!   

LOL!  I'm right there with Andrew.  You definitely win the prize for Best Post Ever, JackieTheBanan!