The gated charge-to-voltage amplifier is designed specifically as an integrating amplifier to measure the area under a narrow pulse. Its capacitor must be discharged before a new sample can be taken. If the initial charge on the capacitor is zero, then the output voltage from the amplifier follows the gate signal. This sampling amplifier is normally used with pulsed signals when the area under the signal is of primary interest. The entire signal is integrated and the output is insensitive to the details of the signal shape.
If the signal pulse rides on a relatively constant but nonzero offset voltage, the effect of the offset can be determined by generating a gate when no signal pulse is present. The resulting output voltage is known as a pedestal and can be subtracted from the data signal at a later point in the system.