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lna buffer biasing is confusing me although S22 is ok.Please help

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s_ss

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Hi,

I am designing an LNA and at the output I have placed a source follower based buffer. This buffer is giving a constant S22 of -15dB from 660MHz onwards. However if I am checking the transient analysis of the buffer, I find that its vgs = 382mV and gm = 3.9mS, vds = 650mV, id = 200uA.

Further if I check the drain current voltage waveform of this buffer I find that the drain current goes down to 200uA. What I want to know if it is ok to have a buffer that work in slightly weak inversion mode i.e vgs<vt and having a current going down to 200uA. This all is not affecting the gain and S22.


Someone please help as soon as possible.
 

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