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Design >> Analog Design >> Fully differential simulation for GBW
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Message started by pipelinena on Feb 15^th, 2008, 6:47pm

Title: Fully differential simulation for GBW
Post by pipelinena on Feb 15^th, 2008, 6:47pm

Hello

I simulated fully differential for Gain/Phase margin/GBW. But probed GBW by single-ended output is half of fully differential output of GBW, only one input terminal added by 1V AC source. What is the true GBW? I use transient analysis and caculated it which is similar to probe singel-end ouptput results.

Thanks

Title: Re: Fully differential simulation for GBW
Post by CherryQ on Feb 19^th, 2008, 7:18pm

Did you use the same load for each diff output?

Title: Re: Fully differential simulation for GBW
Post by Berti on Feb 20^th, 2008, 12:12am

I think there is a bug in your test-bench. Just a guess:
Probably you calculated the GBW directly from the output signal (with calculator from Cadence?). When you take the differential output
you get twice the signal amplitude compared to the single-ended case. Thus, the GBW will double, too.
You should make sure that the input signal is equal 1V AC in differential and single-ended case.

Regards