I am trying to calculate the input impedance of a multiple feedback low pass filter. What I need is the simplest symbolic expression so that later I fill in the values and get the impedence itself:
I assume that I am on the right track in calculation, the thing is I can not go any further and simplify the equation more. Can someone please help with putting calculated $V_2$ (down in the writings) into equation $(2)$ and then put $V_{in}$ into equation $(1)$ and simplify it so that $i_1$ will be removed?
So the question is how to substitute and simplify to get a clear $Z_{in}$ with no current in the final equation.
Thanks in advance!