Analog-to-digital converter using variable counting interval and image sensor including same
AssigneeSamsung Electronics Co., Ltd.
InventorsJin Woo Kim, Seog Heon Ham, Kyung-Min Kim, Yong Lim
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Abstract
An analog-to-digital converter (ADC) within an image sensor includes a comparator comparing a ramp signal with an image signal, and a counter generating a count result in response to the comparison by counting a clock during a counting interval. The ADC determines whether a first counting interval for the counter is less than a reference interval, and if the first counting interval is less than the reference interval the counting interval is a first counting interval, else the counting interval is a second counting interval.
Claims10
An analog-to-digital converter (ADC) configured for use within an image sensor including an array of pixels arranged in a plurality of columns, the ADC comprising:
- a comparator configured to compare a decreasing ramp signal with an image signal provided by a column of pixels and output a comparison result signal;
- and
- a counter configured to receive the comparison result signal and generate a count result by counting a clock during a counting interval,
- wherein the ADC determines whether a first counting interval for the counter is less than a reference interval, and if the first counting interval is less than the reference interval the counting interval is the first counting interval, else the counting interval is a second counting interval;
- wherein the first counting interval is a period extending from a first time when the ramp signal begins decreasing to a second time when the ramp signal is equal to the image signal, and
- wherein the reference interval is equal to a period that is half of a supply period for a count clock signal applied to the counter.
An image sensor comprising:
- a pixel array comprising a plurality of pixels arranged in columns, wherein each column of pixels is configured to provide an image signal;
- a correlated double sampling (CDS) block configured to perform correlated double sampling on the image signal and provide a corresponding CDS output signal;
- a ramp generator configured to generate a decreasing ramp signal;
- and
- an analog-to-digital converter (ADC) configured to receive the CDS output signal and the ramp signal, and comprising:
- a comparator configured to compare the ramp signal with the image signal and output a comparison result signal;
- and
- a counter configured to receive the comparison result signal and generate a count result by counting a clock during a counting interval,
- wherein the ADC determines whether a first counting interval for the counter is less than a reference interval, and if the first counting interval is less than the reference interval the counting interval is the first counting interval, else the counting interval is a second counting interval;
- wherein the first counting interval is a period extending from a first time when the ramp signal begins to decrease and a second time when the ramp signal is equal to the image signal;
- and
- wherein the reference interval is equal to half of a supply period for a count clock signal applied to the counter.
Dependencies are inferred from the claim text.