Guest
|
 Posted:
Thu Dec 08, 2005 9:10 pm Post subject:
pss: "Time steps are continuously to be extremely small." |
|
|
Hi all,
I'm simulation a differential ring oscillator with a frequency of
around 1GHz.
I've successfully used pss and pnoise simulations until I changed the
transistor parameters a bit. Now pss refuses to converge. The transient
simulation shows a nice periodic waveform with a period of about 1ns.
The last messages from the simulator are:
*******************************************************************************
pss: time = 59.21 ns (97.6 %), step = 2.415 ps (234 m%)
Conv norm = 37.2e+03, max dV(I0.dummy_1.I0.load0.D1:int_a) = -63.0052
mV, took
2.61 s.
=======================================
`pss': time = (58.206 ns -> 60.2687 ns)
=======================================
Time steps are continuously to be extremely small.
Conv norm = 347e-12, max dV(I0.dummy_1.delay0.I16.M0:int_d) = -3.77476
fV, took
2.07 s.
Error found by spectre at time = 58.206 ns during periodic steady state
analysis `pss'.
After the dynamic adjustment of tstab, PSS still failed.
*******************************************************************************
Now that looks weird to me. It says "Conv norm = 347e-12, max
dV(I0.dummy_1.delay0.I16.M0:int_d) = -3.77476 fV", but fails to
converge. (It would have covered 2 periods of the signal at that time
from 58.2 to 60.2 ns).
I've tried playing with ireltol, vreltol, step, maxstep with no luck.
Anything else I might try?
Blondie
|
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in