Signal transfer circuitry with offset correction

摘要

Circuitry and method for transferring signals from a photoreceiver array (24) to computational circuitry (21) includes parallel transfer amplifiers (17) that receive periodic offset correction and includes DC removal amplifiers (19). In a first embodiment, each transfer amplifier has a differential circuit (46) that can be switched from a reset mode to a readout mode. In the readout mode, the voltage state at the output (108) is responsive to first and second inputs (74 and 76), with the second input being connected to a source (88) 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 (114) of a fixed reset voltage. An offset adjustment signal (144) 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. In a second embodiment, spatial frequency components of the outputs of the photoreceiver array are removed by DC removal amplifiers (208, 210 and 212). Each DC removal amplifier is assigned to a particular photoelement in the array, but receives outputs (232 and 234) from one or more other photoelements in the array. The output (236) of the amplifier is responsive to the differences between the analog signals input to the amplifier.