Inverting Integrator

The circuit is an operational amplifier used as an inverting integrator. This circuit can be found in multitude of references such as books, magazines, web pages, etc. The peak values of the output voltage is set to ±10 V. This makes the input and output voltages easier to distinguish than when the peak values are equal. Ri = (Vin · deltaT) / (Cint · deltaV) Ri = (5 V · 500 µs) / (0.1 µF · ((10 V) - (-10 V))) Ri = (5 V · 500 µs) / (0.1 µF · 20 V) Ri = 1.25 kΩ "Initial conditions" is set to "User defined". If set to "Determine automatically" the output begins at 0 V. With this starting value the desired waveform can be obtained if the input signal can have a phase shift of 90° but there is no option provided for this. IC (Initial voltage) is enabled for Cint. This is to allow the output voltage to start at the desired positive peak (+10 V) instead of from the maximum positive output voltage (+12 V) of the op-amp. IC (Initial voltage) has an orientation with respect to the schematic symbol. Capacitor Cint is oriented in the diagram otherwise the sign of the initial voltage should be reversed. If a 1.24 kΩ standard value, instead of 1.25 kΩ, is to be used for Ri, the peak output voltage is ±10.081 V. IC (Initial voltage) for Cint should be replaced by 10.081 V. If a 1.2 kΩ standard value, instead of 1.25 kΩ, is to be used for Ri, the peak output voltage is ±10.417 V. IC (Initial voltage) for Cint should be replaced by 10.417 V. Note: For the operational amplifier used in the circuit: Positive voltage swing VOMP = 12 V, Negative voltage swing VOMN = -12 V. When changing the value(s) of resistor, capacitor, and input voltage, the peak values of the output voltage can fall beyond these limits and will be clipped.