Hi,
I'm trying to verify Barchausen criteria for a 4 stage differential ring oscillator and I'm trying to understand the different results I'm getting from stb to pss+pstb using shooting-newton/HB (With diffstbprobe from the analogLib).
Running stb analysis:
As I saw in your workshop (/tools/spectre/examples/SpectreRF_workshop/PSTB.pdf) I should get gain>1 when phase=0.
Is it correct also for differential ring oscillator analysis?
In my analysis the phase doesn't get to 0 at the relevant frequency range.
Running pss+pstb using Shooting-Newton:
Barchausen criteria is met - gain=1 when phase=0.
DC phase is 180 as expected.
Running pss+pstb using HB I'm getting a totally different results:
DC phase is 0. Phase=~60deg when gain=1
What can be the reason for the different results?
Thanks,
Moran