Patent ID: 7268338
Filing Date: 2007-09-11
Classification: H04N

Abstract:
1. An amplifier comprising: an operational amplifier having an input and an output port and a variable feedback capacitor connecting said input and output ports, said variable feedback capacitor having a feedback capacitance determined by a gain control signal, said operational amplifier generating an output signal on said output port related to said feedback capacitance and a charge coupled to said input port; a reset path between said input and output ports, said path having an impedance controlled by a reset signal; and a controller that generates said gain control signal and said reset signal during a charge measurement cycle, said controller generating said reset signal prior to a charge to be measured being transferred to said input port, said controller initially setting said feedback capacitance to a first capacitance value after generating said reset signal, and said controller changing said feedback capacitance from said first capacitance value to a second capacitance value during said charge measurement cycle if said output signal exceeds a first threshold value said amplifier coupling an analog signal from said output port to a circuit external to said amplifier at the end of said charge measurement cycle.