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发表于 2011-8-31 18:30:31
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全差分电路需要共模反馈,我们将反馈回来的vcmfb接在哪里呢?折叠式的情况下通常应该有3种选择,输出级最上面或者最下面的管子,还有一个选择就是接在输入管的电流镜管上,请问这几种接法有什么不同呢??
--> This is not a simple question to be discussed in a few words. In short, CMFB must avoid to be affected by device parameters; and it can not reduce signal swing too much. If wider devices are used to increase output voltage swing, it can increase capacitance (reduce speed). Therefore, different schemes are proposed to optimize the design for different applications. |
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