PSS Problems

Main Page -> Virtuoso -> Cadence 6

Trouble with 'tstab' interval

The timestep collapses to near zero

(1) Set 'relref' to 'sigglobal' which results in a small degradation of accuracy

(2) Set 'lteminstep = tstab time / 1e5' in the 'additionalParams'

(3) Set 'maxiters = 100', 'lteratio = 1e9', and 'maxstep = tstab / 1e4'

Trouble in the shooting interval

(1) Check that 'iabstol > 1e-12'

(2) Specify the divided down frequency as PSS frequency (PSS much simulate one cycle of the periodicity to converge)

(3) Set a longer tstab

(4) Check the tstab stopping point. For a sine wave, you so not want the waveform to stop at a peak or valley. For a square wave, the best stop point is just before the next transition.

(5) Change tstab by a fraction of a period

(6) Do not over-tighten 'reltol' and 'vabstol'. The minimum value for 'reltol' is '1e-6' and for 'vabstol' is '1e-8'