Image sensors having data converters with low noise comparators
AssigneeSemiconductor Components Industries, LLC C
InventorShankar Ramakrishnan
Life of this patent
Estimating the term…
Abstract
An image sensor may include an array of imaging pixels arranged in rows and columns. Each column of pixels can be coupled to a column analog-to-digital converter (ADC) via a pixel output line. The column ADC can include a first low noise single-ended comparison stage, a second low noise single-ended comparison stage, a latch circuit, and a counter. The first low noise single-ended comparison stage may include one or more current source transistors, a voltage ramp generator, a common source amplifier transistor, one or more autozero components, one or more capacitors such as a noise filtering capacitor, and a voltage clamping circuit. The voltage ramp generator can output an increasing voltage ramp or a decreasing voltage ramp.
Claims20
An image sensor comprising:
- a pixel output line;
- a plurality of pixels coupled to the pixel output line;
- and
- a data converter having:
- a first comparator stage having an input formed by a single-ended input transistor and coupled to the pixel output line;
- a second comparator stage coupled to an output of the first comparator stage;
- a latch configured to receive a signal from the second comparator stage;
- and
- a counter configured to receive a signal from the latch.
A data converter operable with an image sensor pixel, comprising:
- a first comparison stage configured to receive a signal, via a pixel output line, from the image sensor pixel and to generate a corresponding output signal;
- and
- a second comparison stage configured to receive the output signal from the first comparison stage, wherein the first comparison stage comprises a common source amplifier transistor having a first source-drain terminal coupled to the pixel output line and having a second source-drain terminal on which the output signal is produced.
A data converter operable with an image sensor pixel, comprising:
- a first comparison stage having a single-ended input transistor, the first comparison stage configured to receive a signal, via a pixel output line, from the image sensor pixel and to generate a corresponding output signal;
- and
- a second comparison stage configured to receive the output signal from the first comparison stage, wherein the first comparison stage comprises:
- a filter capacitor having a first terminal coupled to the pixel output line;
- and
- a voltage clamp having a first terminal coupled to a second terminal of the filter capacitor and having a second terminal coupled to a power supply line.
Dependencies are inferred from the claim text.