Comparator circuit, imaging apparatus using the same, and method of controlling comparator circuit

摘要

An object of the present invention is to provide a comparator which has an input voltage range larger than the case where a conventional offset cancel technique is used, while reducing an offset voltage. A comparator circuit includes: a comparator having an inverting input terminal, a non-inverting input terminal and an output terminal; a first switch having one terminal connected to the inverting input terminal and having the other terminal connected to the output terminal; a first capacitor which has one end connected with the inverting input terminal; a first signal input terminal which is another end of the first capacitor; and a second signal input terminal which selectively inputs either one of a fixed voltage and a comparing signal into the non-inverting input terminal.

主权项

1. An imaging apparatus comprising:
a plurality of pixels arranged in two dimensions, to output a pixel signal based on an incident light; a readout circuit configured to be input the pixel signal, and to output the pixel signal processed; a reference signal generating unit configured to output a ramp signal; and an analog-digital converter, wherein the analog-digital converter is configured to convert the pixel signal into a digital signal, the digital signal having a value corresponding to an amplitude of the analog signal, and wherein the analog-digital converter comprises: a comparator having a first input terminal, a second input terminal and an output terminal; a first switch having terminals, one terminal of the terminals connected to the first input terminal, the other terminal of the terminals connected to the output terminal, and short-circuiting between the output terminal and the first input terminal at a conducting state; a first capacitor having terminals, one terminal of the terminals of the first capacitor receiving the pixel signal, the other terminal of the terminals of the first capacitor being connected to the first input terminal and the one terminal of the first switch; a second capacitor having terminals, one terminal of the terminals of the second capacitor being connected to the second input terminal, the other terminal of the terminals of the second capacitor receiving the ramp signal; and a second switch having terminals, one terminal of the terminals of the second switch being connected to the one terminal of the second capacitor and the second input terminal, the other terminal of the terminals of the second switch receiving a fixed voltage, wherein the analog-digital converter inputs signals output from the readout circuit through the first capacitor, as the pixel signal, and inputs the ramp signal from the reference signal generating unit through the second capacitor.