Pre-amplifier in focal plane detector array
AssigneeIrvine Sensors Corporation
InventorLlewellyn E. Wall
Life of this patent
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Abstract
Circuitry for a focal plane pre-amplifier is disclosed in which the input of the pre-amplifier is switched between the signal from its photo-detector and a connection to ground. During the ground-connected interval, the pre-amplifier transistor is temporarily diode-connected in such a way that the transistor's voltage is stored on a capacitor, which is connected between the incoming photo-detector signal and the input of the pre-amplifier transistor. During the photo-detector connected interval, the voltage stored on the capacitor is subtracted from the voltage signal supplied by the photo-detector.
Claims8
For use in a focal plane optical-electronics system having densely-packed photo-detectors, each electronically connected to a separate amplifier, first stage amplifier circuitry comprising:
- an amplifying transistor whose input receives the signal of a given photo-detector, and whose output amplifies that signal;
- a capacitor connected between the input of the amplifying transistor and the photo-detector output, the output side of the capacitor being connected to the input of the amplifying transistor, and the input side of the capacitor being connected to the photo-detector output;
- first switching means for causing the input side of the capacitor to receive or not receive the signal output of the photo-detector;
- second switching means for causing the input and output of the amplifying transistor to be interconnected or disconnected, in order to provide a diode-connected transistor mode when they are interconnected or an amplifying transistor mode when they are disconnected;
- and
- means for synchronously operating the first and second switching means in order to alternate between (a) storing on the capacitor the voltage across the diode-connected transistor, and (b) subtracting the stored capacitor voltage from the photo-detector signal output when the transistor is in its amplifying mode.
Dependencies are inferred from the claim text.