(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

An n-channel enhancement MOSFET for which V_{t}= 2 V and K = 100 uA/V^{2}is operated from a 9 V supply using a drain resistor R_{D}of 60kohms and the feedback bias scheme depicted. What drain current results? What is V_{D}What is the largest sine wave output signal for which operation in the saturation region is maintained?

2. Relevant equations

3. The attempt at a solution

I'm able to the first two questions but I'm having difficulty with the last sine wave part.

To find Vd and Id, I simply solved (9 - Vd)/60k = (100uA/V^2)(Vd - 2)^2, where I get Vd = 3 V and Id = .1 mA.

To maintain saturation in a n-channel MOSFET this condition: vds >= vgs - vt has to be satisfied. vds >= 3 - 2 = 1. Since Vd = 3 V at DC, then I would think that the sine wave could be +/-2 volts. Unfortunately, the book states the answer is 1.85 volts peak. I think this has to do with the feedback that I may not be correctly taking into account. Does anyone see what I am doing incorrectly?

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# Feedback MOSFET

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