[SOLVED] Why reduce a FET gate poly resistance?

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Hello to all

I'm curious why we need to reduce the FET gate resistance as shown above [Razavi, Design of Analog CMOS Integrated Circuits]

The gate impedance should be high as much as it can, and ideally no current flows through the gate.

so, I don't understand why smaller gate poly resistance is better.

Thanks.
 

Because dynamic current does flow through the gate to charge and discharge the gate capacitance when the MOSFET switches.
So a low gate poly resistance will reduce the gate charge and discharge time, increasing the maximum operating switching speed of the transistor.
 
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