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Measurements >> Phase Noise and Jitter Measurements >> bsim3 vs bsim4 in SpectreRF
https://designers-guide.org/forum/YaBB.pl?num=1121884072

Message started by rcaplan on Jul 20^th, 2005, 11:27am

Title: bsim3 vs bsim4 in SpectreRF
Post by rcaplan on Jul 20^th, 2005, 11:27am

Hi,

I am trying to port a simple ring oscillator VCO to an older process within the same foundry. When I run a pnoise analysis on the present design using a spice BSIM4 model provided by the foundry I get very reasonable results.

The older process provides only a BSIM3 spice model and when I run the exact same circuit with those models, I get an increase in phase noise of almost 40dBc/Hz at the same offset. To rule out actual circuit issues I replaced all the biasing with ideal sources leaving only the ring, and I still see a 30dBc/Hz increase independent of PVT.

If anyone has ideas on what could cause such a discrepancy I would greatly appreciate it.

Regards,

Randy