Hello,

I'm pretty bad and inexperienced at this, so I get easily confused. I am trying to sketch and design a 1st order op-amp low-pass filter circuit that gives signal inversion. Does that mean just a simple op-amp low-pass filter with a NOT gate on the input/output?
This is my sketch for an op-amp low pass filter circuit.

I also want to perform an analysis to find the voltage transfer function. To do this, can I combine C1 and R2 in R2/(1+R2*SC1) where S = j*ω? Is the voltage transfer function the Vo/Vi from which I get the gain?

Thank you

 

This simply op-amp low-pass filter provides "signal inversion" in passband.
And, yes when you find Vo/Vi you will find the "gain".

 

So I got Vo/Vi = (-R2/R1)*[1/(1+S*R2*C1)]. Assuming this is right; I'm told that the bandwidth is 1kHz, and the gain magnitude is 15.
I can use the frequency to find out S, but I still have to find suitable values for the capacitors and the 2 resistors. Do I just assign values that give the expected result? How would I go around this?

 

The voltage gain in the passband is equal to −R2/R1 = 15
And you need a pole at 1Khz.
So simple you can assume R2 = 15K. And now you can easily find the remaining component values.

 

Sorry for being dense, but I'm not quite how to get the value of the capacitor?

 

Pole is located at Fp = 1/(2 * pi * R2 * C2) ---> C2 = 1/(2 * pi * R2 * Fp) ≈ 0.16/(R2 * Fp)

 

Cheers, guys.