Apparatus and method for active integrator optical sensors
AssigneeTexas Instruments Incorporated
InventorsCecil J. Aswell, John H. Berlien, Jr., Eugene G. Dierschke
Life of this patent
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Abstract
Active integrator optical sensor (13) having a photodetector (56) and an active integrator circuit. The active integrator circuit having an operational amplifier (50), an integrating capacitor (51) an offset capacitor (54) and a store capacitor (52). The active integrator circuit operating to integrate the electrical signal from photodetector (56).
Claims19
An optical sensor for use in an optical sensor array to produce an electrical signal in response to electromagnetic radiation, comprising:
- a photodetector having an output proportional to the intensity of the electromagnetic radiation incident with the photodetector;
- and
- an active integrator electrical circuit coupled with the output of the photodetector to accumulate and store the electrical signal from the photodetector, said active integrator electical circuit further comprising:
- an operational amplifier having an offset correction, at least one non-inverting input, at least one inverting input and at least one output;
- a reference voltage supplied to the electrical circuit;
- the photodetector coupled to the operational amplifier inverting input and to the reference voltage;
- an integrating voltage storage device coupled to the operational amplifier inverting input and to the operational amplifier output for storing an accumulated electrical signal from the photodetector;
- a store voltage storage device coupled to the operational amplifier output and to the reference voltage for storing a voltage proportional to the voltage stored on the integrating voltage storage device;
- and
- an output bus coupled to the store voltage storage device;
- and the operational amplifier non-inverting input coupled to the reference voltage.
An optical sensor for use in an optical sensor array to produce an electrical signal in response to electromagnetic radiation, comprising:
- a photodetector having an output that is proportional to the intensity of electromagnetic radiation impinging the photodetector;
- an active integrator coupled to the output of the photodetector, the active integrator comprising:
- an operational amplifier having offset correction;
- an integrating voltage storage device coupled to the operational amplifier, operable to store an accumulated electrical signal from the photodetector during the accumulate and store cycle;
- a offset voltage storage device coupled to the operational amplifier, operable to store a voltage during the offset cycle for operational amplifier offset correction;
- a store voltage storage device coupled to the operational amplifier, operable to store the voltage proportional to the voltage stored on the integrating voltage storage device;
- and
- a reference voltage coupled to the operational amplifier, operable to provide a constant voltage potential to the circuit;
- and
- a switching logic circuit connected to the photodetector and the active integrator, operable to control the timing of the active integrator.
A method of forming an optical sensor array having a plurality of optical sensors which respond to incident electromagnetic radiation, comprising the steps of:
- fabricating each optical sensor from a photodiode having sensor signal output and coupling the sensor signal output from each photodiode with an active integrated electrical circuit;
- supplying a reference voltage to each optical sensor;
- forming the active integrated electrical circuit with an operational amplifier having a non-inverting input, an inverting input and an operational amplifier output wherein the sensor signal output from the photodiode is coupled to the operational amplifier non-inverting input and the operational amplifier inverting input is coupled to the reference voltage;
- forming the active integrated electrical circuit with an integrating capacitor coupled to the operational amplifier negative input and to the operational amplifier output;
- and
- forming the active integrated electrical circuit with an offset capacitor coupled to the operational amplifier and the reference voltage.
Dependencies are inferred from the claim text.