Hi everyone. I'm working on a project where I'm using a current controlled differential amplifier as a VCA followed by an op amp in a differential amplifier configuration with gain. I'm using the op amp to make up gain, because I'm dividing down the input signal going into the VCA stage by 1000 to 1 to stay within the transistor's linear operating region. My problem is to get that gain from the op-amp stage I have to use small values of resistors for the input (R1 in the Vout = R2/R1*vin equation) and it's messing up the operating point of one of the VCA diff-amp stages because of the virtual ground at the inverting input of the op-amp. What would be the best way to solve this problem? I'm thinking of just using another op-amp section as a non-inverting buffer, but that of course uses up another op-amp section for each stage and seems wasteful. I'm wondering if there's a better way to go about doing this? Edit: In my design, I had the VCA set for unity gain at maximum input control current, which necessitated using small collector resistors. Perhaps I could set the VCA to have more gain, and the op amp differential amplifier to have less, and then I could make the input resistors to the op amp larger so they have less effect on the circuit?