Comparator and imaging device
AssigneeSony Semiconductor Solutions Corporation
InventorsMasayoshi Chiba, Shinichi Watanabe
Life of this patent
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Abstract
The present technology relates to a comparator that can easily modify operating point potential of the comparator, and an imaging device. A pixel signal output from a pixel, and, a reference signal with changeable voltage are input to a differential pair. A current mirror connected to the differential pair, and a voltage drop mechanism allowed to cause a predetermined voltage drop is connected between a transistor that configures the differential pair, and a transistor that configures the current mirror. A switch is connected in parallel to the voltage drop mechanism. The present technology can be applied, for example, to an image sensor that captures an image.
Claims11
A comparator comprising:
- a differential pair comprised of:
- a first transistor configured to receive a pixel signal from a pixel unit, and
- a second transistor configured to receive a reference signal from a reference signal output unit;
- a current mirror electrically connected to the differential pair;
- a voltage drop mechanism electrically connected between the current mirror and the differential pair;
- a switch electrically connected in parallel to the voltage drop mechanism;
- a current source electrically connected to the differential pair,
- wherein the current source comprises a third transistor, a fourth transistor and a capacitor,
- wherein the third transistor is electrically connected to the first transistor and the second transistor,
- wherein the fourth transistor is electrically connected to the third transistor, and
- wherein the capacitor is electrically connected to a gate of the fourth transistor.
An imaging device comprising:
- a pixel that outputs a pixel signal as a result of photoelectric conversion;
- a comparator that compares the pixel signal with a reference signal;
- and
- a counter that counts a length of time on a basis of a result of comparison between the pixel signal and the reference signal by the comparator, and determines a count value as a result of analog-to-digital (AD) conversion of the pixel signal,
- the comparator comprising:
- a differential pair comprising:
- a first transistor configured to receive the pixel signal from a pixel unit, and
- a second transistor configured to receive the reference signal from a reference signal output unit;
- a current mirror electrically connected to the differential pair;
- a voltage drop mechanism electrically connected between the current mirror and the differential pair;
- a switch electrically connected in parallel to the voltage drop mechanism;
- a current source electrically connected to the differential pair,
- wherein the current source comprises a third transistor, a fourth transistor and a capacitor,
- wherein the third transistor is electrically connected to the first transistor and the second transistor,
- wherein the fourth transistor is electrically connected to the third transistor, and
- wherein the capacitor is electrically connected to a gate of the fourth transistor.
Dependencies are inferred from the claim text.