Ultra low power solid state spectral radiometer

A method of operation of an adjustable spectral radiometer having a plurality of diodes and associated capacitors in a spectrally sensitive circuit element section, a CPU having a plurality of ports including input and output ports, and having a computer processor, and having a program code residing in memory, and having an associated storage device, and a clock device, and wherein the program code when executed by the computer processor generates instructions causing the computer processor to perform steps of the method, the method comprising the steps of:

• setting, at a beginning measurement cycle at time t0, a state of a first input port of the plurality of ports of the CPU to high-ohmic status and setting a first output port to a low-ohmic status, thus charging the plurality of diodes and associated capacitors, depending on an overall capacitance across the plurality of diodes;
• setting, after a settling time t1, the first input port of the plurality of ports of the CPU to high-ohmic status;
• absorbing, by each selected diode of the plurality of diodes, a specific wavelength range of incoming light depending on bandgap energy of each selected diode, causing generation and recombination of a plurality of photo-induced carriers in each selected diode;
• discharging each selected diode and associated capacitance by the plurality of photo-induced carriers, causing a decrease in voltage across each selected diode, wherein high light intensity causes faster discharge and faster voltage decrease across the plurality of diodes;
• and
• sensing light intensity simultaneously of each selected diode of the plurality of diodes, selected from a group of sensing operations consisting of digital sensing including instructions calculating delay time as a reciprocal of light intensity and analog sensing including instructions recording and measuring changes in voltage as a function of time, thereby determining light intensity.