Recent content by hisotaso

Don't know why itex isn't working, at least on my end...

Ok well I have a line or reasoning that I think works out, please correct me if this is invalid. Roc=\frac{voc}{ic1+ic2} ic1=ic2=ic =\frac{\frac{vc1+vc2}{2}}{2ic} =\frac{\frac{ic*Rc1+ic*Rc2}{2}}{2ic} Rc1=Rc2=Rc =\frac{ic*Rc+ic*Rc}{2*2ic} =\frac{2Rc}{4} =\frac{Rc}{2}

Homework Statement I am learning about differential amplifiers, and am having trouble determining the common-mode output resistance. In the text, we have the two sections "Differential-mode gain and input and output resistances" and "Common-mode gain and input resistance." Notice the lack of...

Homework Statement Pretty straightforward. Attached is a small signal picture of a differential amplifier. Summing currents at the emitter junction, the text says: "Because the transistors have resistive loads, the output resistance will be neglected in the calculations." Why is this...

I found an answer to the question, it is a valid approximation. /closethread

Homework Statement Working through some homework problems we are given the desired gain and input resistance, and are asked to choose what type of amplifier (mosfet or bjt) and what configuration would be ideal. The solutions are given. In the solutions, and in the design example in the text...

Yes I see that it is wrong to compare the two, I realize that the two "Ri's" are not the same. My apologies for not clearer, when I said "I don't understand it" I meant this entire problem, not specifically referring to h-parameter model. I was not posting that to attempt to contradict what...

Thank you for your input. The use/lack of use of ro was a source of confusion for me, and I asked about that somewhere else. I was told that not only would it make a very messy equation, but in fact it had little effect on the results. (I wish the author had explicitly stated this in the text...

I started a second thread because I thought I had figured it out. I stated so in that thread, and thus expected no one would reply. I asked another question about this same circuit in a third thread.

I have had a lot of problems with this text so far, approximations, incorrect solutions...However, I was using this other text on google books as a reference...

Homework Statement THe problem statement and given solutions are in this thread: https://www.physicsforums.com/showthread.php?t=694054 I do not understand the equation for current gain: Homework Equations Ai = \alpha\frac{R4}{R4 + Ri} The Attempt at a Solution I have pages of...

I have figured it out, it's just a current division.

My apologies, it is there now.

Homework Statement Problem statement and solns. in attachment. Homework Equations Can anyone explain the equation for the current gain Ai? I do not understand where the divider temr comes from. The Attempt at a Solution

Homework Statement The problem statement, given solutions, and my small signal drawing are attached Homework Equations Rout, Rin, Av The Attempt at a Solution To begin with, our text seems to alternate between using approximate equations and exact derived equations without stating...