Patent ID: 6635859
Filing Date: 2003-10-21
Classification: G01J,H03M

Abstract:
A light to frequency converter comprising:a temperature coefficient generator responsive to a bandgap reference voltage (VBG) for outputting the bandgap reference voltage with temperature coefficient compensation (VBG_TC); a programmable gain amplifier responsive to the bandgap reference voltage with temperature coefficient compensation (VBG_TC) for outputting an oscillator reference voltage (VREF); and a current controlled oscillator including at least one photodiode configured to receive incident light, the at least one photodiode for generating a photodiode control current, said current controlled oscillator further including a switching capacitor configured to provide a feedback current, said current controlled oscillator responsive to the oscillator reference voltage (VREF), the photodiode control current, and the feedback current for producing an output signal having a frequency proportional to an intensity of the incident light, wherein the bandgap reference voltage with temperature coefficient compensation modifies a temperature coefficient of the switched capacitor feedback current to match a temperature coefficient of the photodiode control current.