An nMOSFET with k 5 1 mA/V2 is to be used as a voltage-controlled resistance, but only over a limited range of vDS values in order to keep nonlinearities low. As we know, the channel resistance in the...

An nMOSFET with k 5 1 mA/V2 is to be used as a voltage-controlled resistance, but only over a limited range of vDS values in order to keep nonlinearities low. As we know, the channel resistance in the limit vDS → 0 is rDS 5 1y(k 3 VOV). However, as vDS is increased, the slope of the iD-vDS curve decreases, so its reciprocal, representing channel resistance, increases from the above value. (a) If VOV 5 1 V, what is the maximum value of uvDSu for which the actual channel resistance deviates by 5% from its value in the limit vDS → 0? What is this limiting value? (b) Repeat, but for VOV 5 2 V, 5 V, 0.5 V, and 0.2 V.