D 5.3 An NMOS transistor fabricated in a technology for which kn′ = 400 μA/V2 and Vt = 0.4 V is required to operate with a small vDS as a variable resistor ranging in value from 200 Ω to 1 kΩ. Specify the range required for the control voltage VGS and the required transistor width W. It is required to use the smallest possible device, as limited by the minimum channel length of this technology (Lmin = 0.18 μm) and the maximum allowed voltage of 1.8 V.
![Problem 5.5(a): An NMOS transistor fabricated in a technology for which kn′ = 511 μA/V2 and Vt = 0.4 V. It is required to operate with a small VDS as a variable resistor by varying the control voltage, VGS, from 0.5 V to 1.0 V. The transistor has the minimum channel length for this technology, Lmin = 0.130 μm. Specify the transistor width, W[ in μm], required to achieve a minimum resistance of 0.3 kΩ.](https://www.doubtrix.com/uploads/editor/4806235779eVSIUJEmgR.jpg)
![Problem 5.5(b): An NMOS transistor fabricated in a technology for which kn′ = 511 μA/V2 and Vt = 0.4 V is required to operate with a small VDS as a variable resistor by varying the control voltage, VGS. The transistor is sized so that (W/L) = 10. Specify the value of VGS [in Volts] required to achieve a resistance of 0.6 kΩ.](https://www.doubtrix.com/uploads/editor/8843347976BUMKQGwWDB.png)
