Method and apparatus for light to frequency conversion

A light controller comprising:

• a monolithic light to frequency converter including a bandgap reference voltage generator for generating a bandgap reference voltage (VBG), a temperature coefficient generator responsive to the 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, said temperature coefficient generator being configured to modify a temperature coefficient of the switched capacitor feedback current to match a temperature coefficient of the photodiode control current;
• and
• a controller responsive to the output signal having a frequency proportional to the intensity of the incident light for controlling a device parameter.

A method for light to frequency conversion comprising:

• generating a bandgap reference voltage with temperature coefficient compensation (VBG_TC) in response to a bandgap reference voltage (VBG);
• providing a programmable gain amplifier responsive to the bandgap reference voltage with temperature coefficient compensation (VBG_TC) for outputting an oscillator reference voltage (VREF);
• and
• providing 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, the current controlled oscillator further including a switching capacitor configured to provide a feedback current, the 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.

A light to frequency converter comprising:

• a voltage generator for outputting a bandgap reference voltage (VBG);
• a programmable gain amplifier responsive to the bandgap reference voltage (VBG) 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.