Patent ID: 8189079

Claim:
An apparatus comprising: a plurality of pixel elements arranged into an array; interface circuitry that is coupled to each of the pixel elements; an input stage including: a plurality of buffers that are each coupled to the interface circuitry; an integrator that is coupled to each of the buffers, wherein the integrator outputs has an adjustable gain, and wherein the integrator includes: a first switch; a first capacitor that is coupled between the first switch and ground; a second switch that is coupled to the first capacitor; a differential amplifier having a first input terminal, a second input terminal, and an output terminal, wherein the first input terminal is coupled to ground, and wherein the second input terminal is coupled to the second switch; and a second capacitor that is coupled between the output terminal and the second input terminal; a comparator that is coupled to the integrator and that compares the analog signal to a threshold voltage; and a coding circuit that is coupled to the comparator and the integrator and that generates a first digital signal, wherein the coding circuit increases the adjustable gain until the analog signal is greater than the threshold voltage; an analog-to-digital converter (ADC) that is coupled to the integrator so as to generate a second digital signal; and an output circuit that is coupled to each of the coding circuit and the ADC so as to generate a third digital signal from the first and second digital signals.