Resettable clamp-sample-and-hold signal processing circuit for imaging sensors
AssigneeHughes Aircraft Company
InventorJohn T. Stein
Life of this patent
Estimating the term…
Abstract
A resettable clamp-sample-and-hold (RC-S/H) circuit includes a preamplifier 12 which buffers and scales a video imaging signal for an RC filter 17. Charge accumulated on the capacitor 16 of the RC filter 17 from previously recovered pixel voltage levels may be removed through a reset switch 18. The scaled video imaging signal may then propagate through a filter buffer 20, a clamp buffer 26 and a sample/hold buffer without the adverse effect of sequential pixel crosstalk.
Claims17
In a signal processor including a clamp-sample and hold circuit having an input stage having a RC filter, including a resistor and a capacitor for noise rejection, the improvement comprising:
- means, connected to said RC filter, for selectively discharging said capacitor prior to receiving a new signal for processing, whereby crosstalk from one signal to a subsequent signal is reduced.
A signal processing circuit, comprising:
- an RC filter, formed of a resistor and a capacitor, said RC filter having buffer means for receiving an input signal for processing;
- means, connected to said RC filter, for selectively discharging the capacitor of the RC filter prior to said filter receiving a new signal for processing;
- means, connected to said RC filter, for receiving a signal from the RC filter and for amplifying said signal;
- a clamping stage for receiving and clamping the signal from the buffer means and for providing an output signal;
- and
- a sample and hold stage for selectively sampling the output signal from the clamping stage and for providing an output, such that input noise is rejected by the RC filter and crosstalk between sequential signals is eliminated by the use of the selective discharging means.
A filter stage of a clamp sample and hold circuit for an imaging sensor, said sensor providing a video signal that indicates sequential pixel readouts, said filter stage comprising:
- means including a capacitance and resistance for removing noise from said video signal;
- and
- means for discharging said capacitance after pixel recovery.
A sensor system comprising imaging sensor means for providing a video signal that indicates sequential pixel readouts;
- and means for recovering said pixel readouts from said video signal, said recovering means including:
- filtering means including a capacitance and resistance for removing noise from said video signal, and discharging means for discharging said capacitance after pixel recovery,
- clamping means, responsive to an output of said filtering means, for clamping the filtered video signal, and
- sampling means, responsive to an output of said clamping means, for sampling and holding the clamped video signal.
Dependencies are inferred from the claim text.