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

Find the output resistance Rout.

[PLAIN]http://img526.imageshack.us/img526/953/pfimg1.jpg [Broken]

2. Relevant equations

[tex]R_{\rm out} \equiv \frac{v_x}{i_x} [/tex]

3. The attempt at a solution

1) Draw small signal equivalent circuit and attach a test source

[PLAIN]http://img101.imageshack.us/img101/3742/pfimg2.jpg [Broken]

2) KCL at source node:

[tex] \frac{0-v_s}{1/g_m} + \frac{v_x - v_s}{r_o} = \frac{v_s}{R_S} [/tex]

[tex] v_x \left( \frac{1}{r_o} \right) = v_s \left( \frac{1}{R_s} + \frac{1}{1/g_m} + \frac{1}{r_o} \right) [/tex]

[tex] v_x \left( \frac{1}{r_o} \right) = \left( i_x Rs \right) \left( \frac{1}{R_s} + \frac{1}{1/g_m} + \frac{1}{r_o} \right) [/tex]

[tex]R_{\rm out} \equiv \frac{v_x}{i_x} = r_o \, Rs \left( \frac{1}{R_s} + \frac{1}{1/g_m} + \frac{1}{r_o} \right) = r_o + \left( r_o \, R_s \, g_m \right) + R_s [/tex]

Is this correct? Thanks.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Output resistance of a MOS current sink

Can you offer guidance or do you also need help?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**