A/D converter circuit and solid-state imaging device

Abstract

Provided are a solid-state imaging device and A / D converter circuit comprising: series-connected capacitative elements; a voltage comparator circuit comparing the output of the capacitative element C1 with a threshold voltage; a first input circuit inputting an analog voltage signal to the node between the capacitative elements C1 and C2; a second input circuit inputting a first reference voltage, monotonously changing in a first conversion process for finding the upper-order bit value, to the node between the capacitative elements C2 and C3; a third input circuit inputting a second reference voltage, monotonously changing in a second conversion process for finding an unconverted bit value after the first conversion process, to the input terminal of the capacitative element C3; and a control circuit generating a control signal to hold the first reference voltage in the capacitative element C3 when the output of the voltage comparator circuit changes in the first conversion process.

Description

technical field [0001] The present invention relates to an A / D conversion circuit for converting an analog signal into a digital signal, and particularly to a solid-state imaging device in which a plurality of solid-state imaging elements for converting an optical signal into an electrical signal are arranged in a matrix. A column-parallel A / D conversion circuit mounted on the same chip. Background technique [0002] A solid-state imaging element (unit pixel) that converts an optical signal into an electrical signal by photoelectric conversion, etc., including a plurality of CMOS imaging sensors, CCD sensors, near-infrared imaging sensors, and far-infrared imaging sensors, etc. is arranged as Among the solid-state imaging devices of the solid-state imaging device group formed in a matrix, there are devices in which analog circuits, digital circuits, and the like are mounted on the same chip. [0003] As a circuit mounted on the same chip as the solid-state imaging element g...

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Problems solved by technology

[0033] In addition, in the case of the column-parallel A / D conversion circuit described in Patent Document 2, for example, when the number of digits of digital data is 10, the number of high-order digits is 5, and the number of low-order digits is 5, The first conversion process takes 2 5 The time of the amount of =32 clocks, the second conversion process needs 2 5 = 32 clocks of time, so a total of 32+32=64 clocks of time is required

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