The discussion revolves around finding the input resistance of an amplifier, with a focus on circuit analysis techniques such as Kirchhoff's Voltage Law (KVL) and Kirchhoff's Current Law (KCL). Participants explore methods for analyzing the circuit presented in a homework problem, discussing the application of different analysis strategies.
Participants generally agree on the use of KVL for circuit analysis but express uncertainty about the necessity of using KVL in every case. There is no consensus on the best approach, as different methods are suggested and debated.
Participants express varying levels of familiarity with amplifiers and circuit analysis methods, indicating that some assumptions about prior knowledge may not hold for all contributors.
This discussion may be useful for students learning about amplifier circuits, circuit analysis techniques, and those seeking clarification on the application of KVL and KCL in practical problems.
gneill said:Write KVL for the left hand loop. Note that ix is the same as ib.
jean28 said:Ok, that worked out pretty nicely! Thank you very much. So just to clarify, when I am doing this type of exercises I need to use KVL's all the time or does it depend? I am really new to amplifiers so I am trying to get where all this is coming from.
gneill said:You use whatever circuit analysis method suits the given circuit arrangement -- choosing which method is simplest to use comes from practice. Here you wanted to find the ratio vx/ix, and those would be principle variables in the KVL for that loop.
I suppose you could apply KCL at node E to find the node voltage there, and then use that and vx to find ix, and then finally determine the ratio vx/ix, but it seems like more work to me.
jean28 said:So I treat it as if I was analyzing any other circuit. Then what exactly does the blue highlighted area mean/represent?