Ad conversion circuit and imaging device

Patent metadata

Field	Value
Publication number	US-2019110012-A1
Application number	US-201816214772-A
Country	US
Kind code	A1
Filing date	Dec 10, 2018
Priority date	Jul 12, 2016
Publication date	Apr 11, 2019
Grant date	—

Abstract

An analog-to digital (AD) conversion circuit includes a digital-to-analog (DA) conversion circuit, an arithmetic circuit, and a comparison circuit. The DA conversion circuit generates a first reference current signal. The arithmetic circuit is electrically connected to the DA conversion circuit and generates a comparison current signal by adding the first reference current signal to a first current signal generated in accordance with a first voltage signal or subtracting the first reference current signal from the first current signal. The comparison circuit is electrically connected to the arithmetic circuit and outputs digital data based on a result of comparing a second current signal according to a second voltage signal with the comparison current signal.

First claim

What is claimed is:

1 . An analog-to digital (AD) conversion circuit, comprising:
a digital-to-analog (DA) conversion circuit configured to generate a first reference current signal; an arithmetic circuit electrically connected to the DA conversion circuit and configured to generate a comparison current signal by adding the first reference current signal to a first current signal generated in accordance with a first voltage signal or subtracting the first reference current signal from the first current signal; and a comparison circuit electrically connected to the arithmetic circuit and configured to output digital data based on a result of comparing a second current signal according to a second voltage signal with the comparison current signal.

2 . An imaging device, comprising:
the AD conversion circuit according to claim 1 ; an imaging unit including a plurality of pixels disposed in a matrix shape, each pixel included in the plurality of pixels configured to output a reset level and a signal level; a column circuit electrically connected to the imaging unit and configured to generate a first pixel signal according to the reset level yard a second pixel signal according to the signal level; a first current generation circuit electrically connected to the column circuit and configured to generate a first pixel current signal according to the first pixel signal; and a second current generation circuit electrically connected to the column circuit and configured to generate a second pixel current signal according to the second pixel signal, wherein the arithmetic circuit is further electrically connected to one of the first current generation circuit and the second current generation circuit, the comparison circuit is further electrically connected to the other of the first current generation circuit and the second current generation circuit, the first current signal is one of the first pixel current signal and the second pixel current signal, and the second current signal is the other of the first pixel current signal and the second pixel current signal.

3 . The imaging device according to claim 2 ,
wherein the first current generation circuit includes a first transistor and a second transistor constituting a first current mirror circuit, and the second current generation circuit includes a third transistor and a fourth transistor constituting a second current mirror circuit different from the first current mirror circuit.

4 . An imaging device, comprising:
the AD conversion circuit according to claim 1 ; an imaging unit including a plurality of pixels disposed in a matrix shape, each pixel included in the plurality of pixels configured to output a reset level and a signal level; a column circuit electrically connected to the imaging unit and configured to generate a difference signal according to a difference between the reset level and the signal level; a reference signal generation circuit configured to generate a reference signal; a first current generation circuit electrically connected to the reference signal generation circuit and configured to generate a second reference current signal according to the reference signal; and a second current generation circuit electrically connected to the column circuit and configured to generate a difference current signal according to the difference signal, wherein the arithmetic circuit is further electrically connected to one of the first current generation circuit and the second current generation circuit, the comparison circuit is further electrically connected to the other of the first current generation circuit and the second current generation circuit, the first current signal is one of the second reference current signal and the difference current signal, and the second current signal is the other of the second reference current signal and the difference current signal.

5 . The imaging device according to claim 4 ,
wherein the first current generation circuit includes a first transistor and a second transistor constituting a first current mirror circuit, and the second current generation circuit includes a third transistor and a fourth transistor constituting a second current mirror circuit different from the first current mirror circuit.

Assignees

• Olympus Corp

Inventors

• Hagihara Yoshio

Classifications

• H03M1/406 Primary

  using current mode circuits, i.e. circuits in which the information is represented by current values rather than by voltage values · CPC title

• H03M1/123

  Simultaneous, i.e. using one converter per channel but with common control or reference circuits for multiple converters · CPC title

• H03M1/745

  with weighted currents · CPC title

• H03M1/46

  with digital/analogue converter for supplying reference values to converter · CPC title

• H04N25/77

  Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components · CPC title