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I've heard that MOSFETs for high frequency circuits are generally configured as common gate.

Can anyone explain why? Could this be related with the internal MOS capacity?

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I think tou are generalizing too much, as MOS are used in high frequency with almost all possible configurations; think to CMOS, in which the basic configuration is common source: it's used in many high-frequency (relatively speaking, as you didn't specify what you mean with "high frequency") circuits. – clabacchio Feb 27 '12 at 9:43

In high frequency RF applications one can get around the miller capacitance by using a cascode which uses the common gate configuration.

Also, It behaves different and as more like a current buffer rather than a voltage buffer. On the wiki page you can see how the gain's behave.

http://en.wikipedia.org/wiki/Common_gate

http://en.wikipedia.org/wiki/Cascode

http://whites.sdsmt.edu/classes/ee320/notes/320Lecture34.pdf

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