Butterworth VCVS filter

[fran1942]

Hello, I am trying to design components for this VCVS Butterworth LPF filter.
My question is regarding Ra and Rb (the feedback resistors)
I am using the formula (K-1)R by using the active filter table. My question are R1 and R2 supposed to be the same ohm value ?

thanks for any help.

 

[godfreyl]

Firstly, your circuit is not a VCVS low pass filter. It should look like the circuit below.

Assuming you are using a table for filters where R1 = R2, C1 = C2 and gain = K, then Rb = (K - 1) * Ra, so they are not the same.