I have a quick question on this example problem on (ideal) OpAmp analysis. I understand the basic cases of negative and positive feedback, and how there is a virtual short between the input pins of the opamp. Things just seem to get a bit confusing once we implement more than one opamp and start connecting inputs and outputs and, welp, I guess I need some help understanding this one:
My steps towards a solution: (Let's call the OpAmp on the left the first OpAmp and the one on the right the second OpAmp)
- There is virtual short between ground and the inverting input on the first opamp. There must be a voltage drop across the first resistor with value R equal to V_in...
- This means a current flows equal to V_in / R through the first resistor. This current cannot go through the OpAmp so it goes through the two 4R resistors.
This is where things get tricky. How do you find the voltage drops across the two 4R resistors? You can't just assume the current is split evenly between the two resistors.
What would the next step be? Any help would be greatly appreciated!