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Design >> Analog Design >> CMFB loop bandwidth requirement for differential amplifier
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Message started by Salim2019 on Mar 15^th, 2019, 4:15pm

Title: CMFB loop bandwidth requirement for differential amplifier
Post by Salim2019 on Mar 15^th, 2019, 4:15pm

Dear friends,
I am designing fully differential amplifier and now I would like to know please what is the relationship between the CMFB loop frequency and the differential signal frequency.

can I CMFB loop with frequency less than the differential mode frequency ?
what is the rule of selecting the CMFB loop frequency ?

Thank you in advance

Title: Re: CMFB loop bandwidth requirement for differential amplifier
Post by Jacki on Mar 17^th, 2019, 1:37am

if you want a stable loop, at least your CMFB frequency should be higher than 3dB frequency in the differential mode.

Title: Re: CMFB loop bandwidth requirement for differential amplifier
Post by Salim2019 on Mar 17^th, 2019, 1:53pm

Dear friend,
Thank you very much for your reply
My CMFB loop is not stable as I came to know that it has higher GBW than the GBW of the differential amplifier and hence polse from differential introduced to it and degraded the stability.

Thus I am going to decrease the CMFB loop bandwidth to improve the stability