the resistance of R1 should be much larger,than xc1 at the possible oscillation frequency , of the circuit (the frequency at which MB = 1 ) to minimize the loop phase shift. R1 should also be much smaller then R2 , to keep the voltage gain high for compensation purposes . A simple rule of thumb is to make R1 = R2/20. Division by any convenient factor up ,to 100 might be satisfactory. If the signal source resistance Rs is substantial, it should be considered part of R1. the voltage gain for determining the op-amp compensating components is then Av = r2/(R1+R2).
Resistor R3 is included in the circuit (as always) to equalize the dc Ib Rb voltage
drop at the op-amp input terminals. since R1 is dc open-circuited by the presence of C1 the total resistance in series with the op-amp inverting input terminal is the resistance of R2 .therefore, R3 should equal R2
Example 8-1
design a differentiating circuit to give an output of 5 v when the input changes by 1 v
in a time of 100 us. use an op amp with a bipolar input stage