# Combination Network

Discussion in 'Electronics Homework Help' started by jkele, Mar 19, 2011.

1. ### jkele

13
0
Nov 21, 2010
I have attached a image, in that image is the 3.3kOhm resistor in series or parallel with the 100kOhm?

My solution is, if the current flows down from the dependent source and up through the 3.3kOhm resistor, it splits at this point and goes to the 100kOhm resistor. Hence it is in parallel?

http://img718.imageshack.us/i/61943863.jpg/

Last edited: Mar 19, 2011
2. ### Laplace

1,252
184
Apr 4, 2010
The question does not make sense. The presence of the op amp changes everything.

3. ### jkele

13
0
Nov 21, 2010
so the answer is they are neither in series nor in parallel?

4. ### Laplace

1,252
184
Apr 4, 2010
It appears that the circuit consists of an equivalent model of a transistor in a CE configuration with a 3.3K load resistor and the collector tied directly to the virtual ground, '-' input, of the op amp so that both ends of the load resistor are at signal ground. All of the output signal current must then flow through the 100K feedback resistor.

5. ### lexroxas

37
0
Apr 15, 2011
They are not in parallel and they are also not in series. Your circuit is an inverting operational amplifier that uses 100K resistor as the feedback resistor and the 3.3k resistor as the input resistance. The voltage gain of this inverting OP amp is given by the formula Vout = 1 + (100k/3.3k). Study the basics of operational amplifiers.