# Homework Help: Differential Amplifier, Single-Sided

1. Oct 19, 2008

### birdgirl

1. The problem statement, all variables and given/known data

I need to calculate Vo in the image of the circuit (bitmap image link follows):

http://www.filedropper.com/circuit"

All the information provided is in that diagram - since we are studying differential amplifiers, I assume all the beta values are equal.

2. Relevant equations

IC = BIB
IE = (B+1)IC
V=IR

3. The attempt at a solution

I understand that this is a single-sided diff. amp., single-sided, which means I should start with a DC analysis and then replace with an equivalent circuit. However, most examples I have seen (actually, all) have an RE in place of the whole lower transistor circuit...so I don't know how to go about solving for the current, which I would normally get by 12 - 0.7 = IRE.

I saw a suggestion that I use ro, but I don't have that value, and don't think I can calculate it.

I also saw this described as having a constant current source, but then it hopped over all the steps and I didn't know how to use that knowledge.

Any help with a starting point for this question would be greatly appreciated.

Last edited by a moderator: Apr 23, 2017