Patent ID: 7420152
Filing Date: 2008-09-02
Classification: H03F

Abstract:
1. A sensing and conditioning system comprising: an analog light sensor capable of converting a sensed input surface into an analog sensor current signal indicative of a range of, an amount of, an intensity of, or an exposure of the sensor to light; an operational amplifier having an inverse input connected to the analog light sensor, and a non-inverse input being connected to a ground, the amplifier providing an amplifier output signal at an amplifier output; an amplifier feedback loop having a resistor connected between the amplifier output and its inverse input to provide a feedback current signal at the amplifier inverse input; a comparator having a first comparator input connected to the output of the operational amplifier and a second comparator input connected to a reference circuit providing a reference signal, so that the comparator provides an output signal at a comparator output that reflects a comparison between the amplifier output signal and the reference signal; a control circuit having a control circuit input connected to the output of the comparator with said control circuit receiving the output signal from the comparator and, in response thereto, generating a control circuit output signal that has at least an integration component; and an offset source circuit having an offset input connected to the control circuit output and an offset output connected to the inverse input of the operational amplifier, and being adapted to generate an offset current signal at the offset output based upon the control circuit output signal, said offset current signal tending to minimize the difference between the light sensor signal and the feedback signal, so that said amplifier output signal will be controlled to be close enough to the reference signal to cause the control circuit output signal to be proportional to the light sensor signal.