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noise of the gate of mos?

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shanmei

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it is said that mos has a resistive channel, so it has thermal noise, just like other
resistor. But the gate resistance is huge, in this way is it will exhabit thermal nosie?
 

Noise of poly gates is not important if it is low frequency because gate is floating, however in the case of LNA you have to decrease the resistance of poly.
 

yxo said:
Noise of poly gates is not important if it is low frequency because gate is floating, however in the case of LNA you have to decrease the resistance of poly.
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so do you mean that since it is floating , it do not contribute noise to the output.
 

Yes, I believe so. High resistance of gate to channel can be represented as a shunt resistance. You can convert the shunt resistance to the series one using 4-port network and find out that high shunt resistance coresponds to low series one.
 

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    shanmei

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yxo said:
Yes, I believe so. High resistance of gate to channel can be represented as a shunt resistance. You can convert the shunt resistance to the series one using 4-port network and find out that high shunt resistance coresponds to low series one.
Click to expand...

YXO,

do you mean the gate resistance shunt with the rds of the MOS(Rgate // rds),
since Rgate>>rds, so the overall resistance is about rds.??
 

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