Offset removal circuitry for photoreceiver signals
First Claim
1. A method of providing offset correction to a differential circuit that is periodically switched between readout operations and reset operations, said differential circuit having first and second circuit inputs and a circuit output for which an output voltage condition is responsive to voltage states at said circuit inputs, said method being carried out for at least some of said reset operations and said method comprising:
- (a) connecting said first circuit input to said second circuit input when said differential circuit is switched from a readout operation to a reset operation;
(b) connecting said circuit output to a source of a fixed voltage state when said differential circuit is switched from said readout operation to said reset operation;
(c) disconnecting said circuit output from said source following a first time segment of said reset operation, thereby initiating a second time segment of said reset operation in which said circuit output is free to float from said fixed voltage state; and
(d) forming an offset correction signal in response to a shift of a voltage condition at said circuit output during said second time segment.
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Accused Products
Abstract
A method for transferring signals from a photoreceiver array to computational circuitry in which parallel transfer amplifiers receive periodic offset correction. In a first embodiment, each transfer amplifier has a differential circuit that can be switched from a reset mode to a readout mode. In the readout mode, the voltage state at the output is responsive to first and second inputs, with the second input being connected to a source of a reference voltage. In the reset mode, the inputs are both connected to the reference voltage and the output is temporarily connected to a source of a fixed reset voltage. An offset adjustment signal is generated in response to detection of a voltage difference between the reset voltage and the actual voltage state at the output after the output has been disconnected from the source of the reset voltage. A single offset circuit is used to periodically and sequentially refresh the various transfer amplifiers.
13 Citations
10 Claims
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1. A method of providing offset correction to a differential circuit that is periodically switched between readout operations and reset operations, said differential circuit having first and second circuit inputs and a circuit output for which an output voltage condition is responsive to voltage states at said circuit inputs, said method being carried out for at least some of said reset operations and said method comprising:
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(a) connecting said first circuit input to said second circuit input when said differential circuit is switched from a readout operation to a reset operation; (b) connecting said circuit output to a source of a fixed voltage state when said differential circuit is switched from said readout operation to said reset operation; (c) disconnecting said circuit output from said source following a first time segment of said reset operation, thereby initiating a second time segment of said reset operation in which said circuit output is free to float from said fixed voltage state; and (d) forming an offset correction signal in response to a shift of a voltage condition at said circuit output during said second time segment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification