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The output resistance of CMOS?

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roy2li

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cmos output impedance

How to obtain it?
and what is the relations with the source/drain resistance of mosfet?

For an individual mosfet, is the output resistance equals to the source/drain resistance?

Thanks in advance!
Regards!

Roy
 

cmos output resistance

To measure it experimentally you can obtain the waveforms of the voltage and current on the output and then divide them with an digital oscilloscope, and with a single mosfet you can assume that the output resistance is the drain resistancei you look it from the drain and the inverse of the transconductance if you look it from the source.
 

mos output resistance

There is a difference between small signal resistance and large signal resistance
 

output resistance cmos

The output resistance of CMOS...

low

CMOS uses a complimentary pair. Either the one or the other is on at any one time (assuming not in transition). Thevnin says short V to ground. Therefore, you have a low resistance (an on mosfet) to ground. And, it makes sense to some extent, as CMOS drives many CMOS gates. You don't drive much from a high impedance, except much much higher impedances. (One CMOS can drive many (parallel! -- Rp<lowest R ) CMOS gates -- it has to be low Zout.)

Sorry, I avoid actual numbers as much as possible. ...and hope the circuit doesn't blow up!
 

output resistance in cmos

Hi,
In CMOS circuits either PMOS or NMOS is on at a time.
To calculate the output resistance we take the transistors which are on.
The ON output resistance is Vds/Ids.
Than we use series or parallel combination of all the on transistors to calculate the output resistance.
This is the technique which is used to find the rise time and the fall time(RC).

Thanks
Shaikh Sarfraz
 

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