An autozeroing operational amplifier for a voltage or current-to-frequency converter includes a master amplifier and a slave amplifier. The master amplifier uses the voltage across a master capacitor to control the polarization level of an MOS transistor. Changing this level changes the operation of a differential pair connected to a load thereby changing the amplifier's input offset voltage. The slave amplifier, similarly constructed, is connected to periodically refresh the voltage across the master capacitor to compensate for drift and temperature effects.