Comparator with correlated double sampling scheme, cmos image sensor including the same, and operating method thereof
AssigneeSK hynix Inc.
InventorTae-Gyu KIM
Life of this patent
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Abstract
A comparison device includes; a comparison block suitable for comparing a pixel signal with a reference voltage including a ramp-up signal and a ramp-down signal; a correlated double sampling (CDS) block suitable for performing a correlated double sampling operation on the pixel signal; a first switch suitable for selectively inputting the ramp-up signal as the reference voltage based on a first switch control signal; a second switch suitable for selectively inputting the ramp-down signal as the reference voltage based on a second switch control signal; and a feedback control unit suitable for generating the first and second switch control signals based on a result of the comparison during an initialization operation.
Claims17
A comparator for an image sensor, the comparator comprising:
- a comparison block suitable for comparing a pixel signal with a reference voltage including a ramp-up signal and a ramp-down signal;
- a correlated double sampling (CDS) block suitable for performing a correlated double sampling operation on the pixel signal;
- a first switch suitable for selectively inputting the ramp-up signal as the reference voltage based on a first switch control signal;
- a second switch suitable for selectively inputting the ramp-down signal as the reference voltage based on a second switch control signal;
- and
- a feedback control unit suitable for generating the first and second switch control signals based on a result of the comparison during an initialization operation.
An operating method of an image sensor, the operating method comprising:
- comparing a pixel signal to a ramp signal during an initialization operation;
- generating a control signal for selecting a ramp-up signal or a ramp-down signal based on a result of the comparison;
- and
- selecting the ramp-up signal or the ramp-down signal as the ramp signal based on the control signal to perform a comparison operation using the selected ramp signal.
An image sensor comprising:
- a pixel array suitable for outputting a pixel signal corresponding to incident light;
- a ramp signal generation circuit suitable for generating a ramp-up signal and a ramp-down signal;
- a comparison circuit suitable for selecting the ramp-up signal or the ramp-down signal based on a value of the pixel signal during an initialization operation, comparing a value of the pixel signal with a value of the selected ramp signal and generating an output comparison signal;
- a counting circuit suitable for performing a counting operation on the output comparison signal;
- a memory circuit suitable for storing data representative of the counting information outputted from the counting circuit;
- a column readout circuit suitable for outputting the data of the memory circuit;
- and
- a control circuit suitable for controlling operations of pixel array, the ramp signal generation circuit, the comparison circuit, the counting circuit, the memory circuit and the column readout circuit.
Dependencies are inferred from the claim text.