Patent ID: 7139024

Claim:
An imaging system comprising: first and second differential data lines; a plurality of pixels, each pixel including a sensor and a comparison circuit, the comparison circuit including a first input terminal connected to the sensor, a second input terminal connected to receive a global ramp voltage, and means for comparing a sensor voltage generated by the sensor with the global ramp voltage, for transmitting a first differential current onto the first and second differential data lines when the sensor voltage is less than the global ramp voltage, and for transmitting a second differential current onto the first and second differential data lines when the sensor voltage is greater than the global ramp voltage; and a comparator output circuit for generating a comparator output signal that has a first value when the first differential current is transmitted on the first and second differential data lines, and has a second value when the second differential current is transmitted on the first and second differential data lines, wherein the comparator output circuit includes means for keeping constant voltages on the first and second differential lines when currents on the first and second differential lines change from the first differential current to the second differential current.