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Design >> Analog Design >> unity gain bw of a push pull aplifier
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Message started by mixed_signal on Oct 19^th, 2011, 1:32am

Title: unity gain bw of a push pull aplifier
Post by mixed_signal on Oct 19^th, 2011, 1:32am

Hi,
I want to find the ugb of a push pull aplifier. What is the simplest method to do it? Is it gm/cL? In allen Holdberg the open loop gain and 3db pole is calculated. What if I multiply both and get UGB?

Title: Re: unity gain bw of a push pull aplifier
Post by thechopper on Oct 19^th, 2011, 5:28am

why not?
If your non-dominant poles are higher than your GBW then your calculation will be correct.

Best
Tosei

Title: Re: unity gain bw of a push pull aplifier
Post by mixed_signal on Oct 19^th, 2011, 11:48am

Thank you thechopper. But what about gm/cL? Will it work?

Another method is gm/C1 where C1 is responsible for dominant pole. What about this method? :)

Title: Re: unity gain bw of a push pull aplifier
Post by raja.cedt on Oct 20^th, 2011, 12:28am

both are correct, UGB=gm/(c), where c is the cap which is responcilbe for dominate pole, so take a amp which has dominate pole at at load so UGB=gm/cl, or consider miller compensated opamp there cc is responcible for dominate pole, so ugb=gm/(cc)

Thanks,
raj.

Title: Re: unity gain bw of a push pull aplifier
Post by mixed_signal on Oct 20^th, 2011, 11:26am

Thank you raj!