I read in a book that perfect integration using inverting op-amp is possible only when the time constant of the circuit(R1Cf) is lesser than the time period of the input signal. I have trouble in understanding this concept. Lets assume i give a square wave as input at the inverting terminal.Now the output would ramp down when the input is positive and since the time constant is less than time period would not the capacitor charge soon (before the cycle completes)and behave as an open circuit making the op-amp work as though in open-loop configuration? Now since the open loop gain is very high would it not saturate? How then can it integrate properly? On the other hand if time constant is greater than time period of the input signal cant it integrate properly?