ESR of an NMOS realized CAP

[kumar123]

Hi
i understood ESR is nothing but effective series resistance(inherent) of an capacitance , it is same for NMOS realized capacitors

can anybody know how to extract ESR of an NMOS CAP?

what analysis needs to be done on this to get accurate ESR value in SPICE?
(i feel it may depend on Voltage,freequency of excitation and temperature)

actually i tried using known R in series with NMOS realized CAP and given to DC voltage of V. This is based on Charging Timeconstant princeple of capacitor

when i print Voltage across capacitor i have not seen it is rising(usually every cap has to rise exponentially towards V)insted at t=0s itself it has reached to V

any information on this is appreciable

Thanks
Kumar

 

[Vamsi Mocherla]

The resistance of the polysilicon used by the gate will give the ESR of the NMOS Cap. But, since it is salicided, I do not think that it will contribute to a whole lot. But why are you so concerned about the ESR of an integrated cap?

 

[laglead]

In addition to poly, channel carrier limited mobility also make NMOS appear to have ESR.