Coherent sampled readout circuit and signal processor for a charge coupled device array

Claim 1

A circuit for providing coherent readout and signal processing of charge coupled device (CCD) apparatus having a plurality of clocked transfer electrodes, comprising in combination: a minority carrier detector circuit; a minority carrier switch, including a control electrode coupled to a periodic control signal, located between said detector circuit and a transfer electrode of said CCD apparatus and being operable in response to said control signal during a third predetermined time subinterval of a minority carrier transfer clock period to gate a minority carrier charge packet into said detector circuit; a field effect device of a first semiconductor type, operable as a reset switch, coupled between a Predetermined reference voltage and said detector circuit, and being operable in response to another periodic control signal for being rendered conductive during a first predetermined time subinterval of said clock period; a field effect device of a second semiconductor type, operable as an amplifier, having an input electrode coupled to said first type field effect device and said detector circuit at a common circuit junction, said junction providing a node capacitance thereat which is charged to said reference voltage during said first time subinterval; a sample and hold circuit including a first capacitor coupled to an output electrode of said second type field effect device, a first electrically operated switch device coupled to said first capacitor and being operable in response to still another periodic control signal for closing said switch means during a second predetermined time subinterval of said clock period whereby said first capacitor charges to said reference voltage appearing across said node capacitance, said minority carrier switch thereafter becoming operable during said third time subinterval wherein a minority carrier charge packet is coupled to said detector circuit and a signal voltage indicative thereof coupled to said first capacitor wherein a voltage subtraction process results, and a second electrically operated switch device operable in response to yet another periodic control signal for controlling said second switch during a fourth and last predetermined time subinterval of said clock period and a second capacitor coupled to said second switch device, said second capacitor sampling the voltage on said first capacitor during said fourth time subinterval and providing a video signal of said minority carrier signal thereacross.

Claim 10

The method of operating a charge coupled device circuit for providing coherent readout and signal processing of minority carrier signal packets, comprising the sequential steps of: turning ''''on'''' a semiconductor reset switch and applying a reference voltage VR across a circuit node capacitance having a common connection with a minority carrier detection circuit, said voltage VR having an uncertainty expressed by the Nyquist noise voltage (Vn2)1/2 (KT/CN)1/2 when applied across said circuit node capacitance; turning ''''off'''' said reset switch; reading and holding said reference voltage appearing across said node capacitance by coupling a capacitor across said node capacitance; uncoupling one side of said capacitor from one side of said node capacitance while remaining coupled to said detection circuit; coupling a minority carrier signal packet into said detection circuit wherein said minority carriers change the charge state of said node capacitance and said capacitor; and reading the voltage across said capacitor; and sampling the voltage across said capacitor which comprises the difference between said reference voltage and the signal plus said reference voltage thereby removing said Nyquist voltage and switching transients from the signal output to improved dynamic range and provide 1/f noise filtering of the circuit.

Claim 11

The method of operating a charge coupled device circuit for providing coherent readout and signal processing of minority carrier signal packets, comprising the sequential steps of: turning ''''on'''' a semiconductor reset switch and applying a reference voltage VR across a circuit node capacitance having a common connection with a minority carrier detection circuit, said voltage VR having an uncertainty expressed by the Nyquist noise voltage (Vn2)1/2 (KT/CN)1/2 when applied across said circuit node capacitance; turning ''''off'''' said reset switch; reading and holding said reference voltage appearing across said node capacitance by coupling a capacitor across said node capacitance; uncoupling one side of said capacitor from one side of said node capacitance while remaining coupled to said detection circuit; coupling a minority carrier signal packet into said detection circuit wherein said minority carriers change the charge state of said node capacitance and said capacitor; and reading the voltage across said capacitor; and sampling the voltage across said capacitor which comprises the difference between said reference voltage and the signal plus said reference voltage thereby removing said Nyquist voltage and switching transients from the signal output to improved dynamic range and provide 1/f noise filtering of the circuit.