Low power integrating circuit for use with a photodetector and optical sensor including such an integrating circuit

An integrating circuit for use with a photodetector having an output supplying an electrical signal proportional to the intensity of the electromagnetic radiation striking the photodetector, said integrating circuit comprising:

• an operational amplifier having a non-inverting input connected to a non-zero bias voltage, an inverting input capable of being coupled to said photodetector, and at least one output;
• an integrating voltage storage device having a first terminal coupled to the operational amplifier output and a second terminal coupled to the operational amplifier inverting input;
• an output stage comprising a gate terminal connected to the operational amplifier output and an output terminal connected to said first terminal of the integrating voltage storage device;
• and
• switching circuitry for controlling timing of the integrating circuit and switching the integrating circuit between a reset phase and an integration phase,
• wherein said switching circuitry includes means for balancing said operational amplifier and developing a voltage across said integrating voltage storage device during said reset phase, which voltage is substantially equal to said bias voltage, said first terminal of the integrating voltage storage device being pulled to a reference potential during said reset phase.