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Design >> Analog Design >> ac simulation with sc cmfb in an telescopic opamp
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Message started by zychang on Oct 19^th, 2006, 7:24am

Title: ac simulation with sc cmfb in an telescopic opamp
Post by zychang on Oct 19^th, 2006, 7:24am

Hi all,

I just have a little problem doing the ac analysis of the opamp. It is a fully differential telescopic opamp with a switched-capacitor CMFB(common mode feedback) circuit. At first, I simulate the opamp with a sort of ideal CMFB and got the gain and UGB I want. Then, I put in the SC CMFB and did a tran analysis to see how many clock cycles the output CM needed to settle. After finishing both steps, I was trying to see how much gain and UGB I got with this SC CMFB. But here is the thing, how could I do the AC analysis with the output CM needs to settle in some clock cycles? Is there anyone having done this before could give me some advice? thanks in advance.

Mike

Title: Re: ac simulation with sc cmfb in an telescopic op
Post by Ken Kundert on Oct 19^th, 2006, 5:28pm

Use the PAC analysis of SpectreRF.

-Ken