EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: EEM on June 26, 2016, 05:07:56 am
-
Hello, I am hoping someone could help me with part B of this problem. I am not sure of the effects the resistor would have on the differential output gain.
Also I have attached my solution to part A but I am uncertain if I derived it correctly.
Any help would be appreciated !
-
b. A resistor between outputs acts in parallel with (Rc + Rc), so reduces gain by that amount. No effect on CM.
Tim
-
Thanks Tim !
I've attached my proof for b. Does this look OK ?
Also, I thought the added resistor would affect Vo1, so why would there be no effect on CM gain ?
-
b. A resistor between outputs acts in parallel with (Rc + Rc), so reduces gain by that amount. No effect on CM.
With common mode gain they mean the gain for a single ended output (not the differential gain with transistor mismatch as is common). Because of Ree this will change.
-
Hmm, it should be 3, not 4.
What is the definition of differential output voltage? Common mode?
Tim
-
delta[Vout(diff)] = delta [Vout(1) - Vout(2)]
delta[Vout(cm)] = (1/2) x delta[(Vout1 + Vout2)]
-
I've attached my proof for b. Does this look OK ?
No - it doesn`t.
You have forgotten that the third (new) resistor is not at signal ground at one leg.