Charge amplifier

A charge amplifier is a current integrator that produces a voltage output proportional to the integrated value of the input current. The amplifier offsets the input charge using a feedback reference capacitor, and produces an output voltage inversely proportional to the value of the reference capacitor but proportional to the total input charge flowing during the specified time period; hence the circuit acts as a charge-to-voltage converter. The gain of the circuit depends on the value of the feedback capacitor.