if a mos is to used as a 100K resisitor,,
Its Vs =Vo+vx
Vd=Vo-vx
Vg=Vbias,values of Vo=0.5v,vx is an ac signal with utmost 0.2v amplitude,,wat should be the value of Vbias if the nonlinear part of the current in the resistor is utmost 5%..
in this how to model the nonliearity?
1> why not use a nwell or poly or pplus resistor for 100k?
2> if mos used for resistor, it should work in linear region, gate usually pull to VDD or GND, why need a Vbias??
if a mos is to be used as a resistor, I has got to work in its triode region, not in saturation region. Because when working in the triode region, the linearity is there. once you increase the Vds, your current increases.
this is the MOS that needs to be biased as a resistor,,n have to determine the W/L value too ,,
what ll be the effects of non linearity in this n how to model it [/img]
To find out the value of W/L u can use this formula:
R = 1 / (un*Cox*(W/L)*Vov) ..Vov = overdrive
Refer Johns and Martin..
They have used Mos as a resistor in Opamp compensation..
I hope this helps
BR
Vabzter