Hello Group,
I need some tips on the deviration of a transfer function for an op-amp circuit that is in "Troubleshooting Analog Circuits" by Bob Pease, pg.
- I do not want anyone to solve it for me; rather, I would like a sanity check on my loop equations that I am coming up with using Mesh Analysis to determine the transfer function...and...if there is an easier way. Once I get the loop equations, that leaves me with three equations and a big ass determinant to deal with. There must be an easier way and/or something that I am missing. A single resistor between the terminals shouldn't cause this much trouble :-(
I am assuming clockwise for all currents in each window and analyzing clockwise as well. The loop equations I am coming up with are:
Loop1: Vin - I1(R3+R4) + (I2*R3) + (I3*R4) = 0 Loop2: Vin + (I1*R3) - I2(R1 + Rb + R3) + (I3*Rb) = 0 Loop3: -(I1*R4) - (I2*Rb) + I3(R4 + Rb + R2) = Vo
Mr. Pease states that the transfer function is: Vout/Vin = (1 + R2/R1) + ((R2 + R4)/Rb)
Link to circuit: