Integrating capacitively coupled transimpedance amplifier

摘要

An amplifier circuit 12 for an infrared detector 10 in a detector array formed on a large-scale integrated structure. The amplifier circuit is fabricated along with the detector on the structure and includes an amplifier stage capacitively coupled 14 to the detector 10 and an output stage. A switching FET 16 is provided to selectively couple the detector to an external biasing source and another switching FET 24 is provided to reset the amplifier stage after an integration period. In one embodiment the output stage 28 includes a storage capacitor 30 selectively coupled to the amplifier stage by a switching FET 32. In another embodiment the output encoding stage 28 includes a two-gate FET 32 to control the voltage on a storage capacitor 30. The two-gate FET controls a voltage source which periodically pulses and drains the capacitor. One FET gate is connected to the amplifier stage output and the other is connected to a clocking signal. In still another embodiment the output stage 128 includes a second capacitor 132 of smaller capacitance onto which a charge of the first capacitor 130 proportional to the output of the amplifier stage is placed for subsequent sampling.