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Simulators >> Circuit Simulators >> How to simulate the opamp with dynamic CMFB?
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Message started by sch on May 20^th, 2003, 1:28am

Title: How to simulate the opamp with dynamic CMFB?
Post by sch on May 20^th, 2003, 1:28am

I have a opamp with dynamic switched capacitor common mode feedback and want to know how to simulate the DC gain of opamp with dynamic CMFB, if use the Spectre command PAC and PSS ??

Title: Re: How to simulate the opamp with dynamic CMFB?
Post by Paul on Jun 5^th, 2003, 2:35am

I guess you should replace the switched capacitors by their equivalent resistors.

Paul

Title: Re: How to simulate the opamp with dynamic CMFB?
Post by August West on Jun 5^th, 2003, 9:45am

I recommend using PAC. If you didn't have the dynamic CMFB you would use AC, presumably using one of the techniques that Kundert talks about in his book (section 3.4.1), such as Middlebrook's method, to avoid the problems that occur when you open the loop. With dynamic CMFB, you would do exactly the same thing, except replace the DC analysis with a PSS analysis and replace the AC analysis with PAC.

-August