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**1. Homework Statement**

Given the following circuit find the input resistance as seen through vo.

**2. Homework Equations**

**3. The Attempt at a Solution**

To solve this problem I started by drawing the signal equivalent circuit:

As we can see the voltage v

_{gs}= v

_{i}- v

_{o}. To find the input resistance I used Thenevin's theorem, placing a DC test voltage, V

_{T}, between the output terminals. By finding the relationship between V

_{T}and the current that passes throught it I hoped to find the value of the input resistance.

This, however, didn't take me to the correct result. I was told the result was equal to 1/g

_{m}|| r

_{o}|| R

_{s}. I do not understand how to get to this result tho.. If someone could point me in the right direction I'd appreciate!