请教关于全差分运放CMFB

CuiBing

共模反馈的带宽要大于等于差模是因为：当输入共模电平增大或减小时，检测到的共模电平也相应增大或减小，增大或减小的量必须立刻反馈到被控制的电流源上，这样才能起到立刻调节的作用。达到速度上的匹配（带宽决越大响应越快）

lightgo

文献中很多直接引用结论：CMFB的低频增益应足够大，与差模增益可比；CMFB单位增益带宽最好大于差模单位增益 ...
dyjguilin 发表于 2008-3-22 15:18

                               
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On system-level, you should first make clear how your input-signal looks like. What is ur signal-modulation type? How much common-mode variation will happen?
On circuit-level, make clear how much SNR your amplifier needs to provide? How much common-mode to diff-mode conversion is tolerant?

after these considerations, you can define your CMRR and CMFB BW clearly.

BR, lightgo

jackaq

Brendan

我觉得CMFB的GBW需要要大于Common Mode的GBW