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Design >> Analog Design >> Having no CMFB designed yet how to first design the main op amp
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Message started by pdirac on Aug 6^th, 2019, 8:53pm

Title: Having no CMFB designed yet how to first design the main op amp
Post by pdirac on Aug 6^th, 2019, 8:53pm

I'm trying to design a fully differential folded cascode op amp with a SC-CMFB circuit to fix the output common mode voltage. The problem is that the design of the main op amp depends on the bias voltages and all that sort of stuff. If the output common mode is not set yet then how should I be able to first to a dc analysis to make sure every transistor is in saturation?To get the output impedance, dc gain, UGB, etc. all require to have the node voltages already determined. Some people suggested a VCVS to first fix the output common mode voltage. But how is that implemented?