CMOS image sensor outputting signal data before reset data and method for driving the same
AssigneePixelplus Co., Ltd.
InventorSeo Kyu Lee
Life of this patent
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Abstract
A CMOS image sensor that outputs signal data before outputs reset data, and a driving method therefor. The CMOS image sensor includes a pixel sensor, a data I/O line, a double sampling circuit and an output circuit. The pixel sensor generates signal data and reset data. The signal data has a voltage level depending on an amount of photo-charge produced in response to energy received externally. The reset data is produced in a reset mode. The data I/O line transfers the generated signal data and the reset data. The double sampling circuit samples the signal data and then the reset data, from the data I/O line, and drives an output terminal. The output circuit outputs data related to a voltage level of the output terminal.
Claims14
A CMOS image sensor, comprising:
- a pixel sensor having a reset mode, the pixel sensor generating reset data in the reset mode, the pixel sensor further generating signal data, the pixel sensor being responsive to energy received externally, for generating the signal data, the pixel sensor producing an amount of photo-charge according to the amount of the received energy and converting the produced photo-charge to the signal data, the signal data having a voltage level depending on the amount of the produced photo-charge;
- a data I/O line carrying the signal data and the reset data generated in the pixel sensor;
- a double sampling circuit coupled to the data 110 line for sampling the signal data and the reset data, and driving an output terminal;
- and
- an output circuit for outputting data related to a voltage level of the output terminal,
- wherein the double sampling circuit samples the signal data before sampling the reset data.
A CMOS image sensor, comprising
- a pixel sensor generating signal data, and generating reset data in a reset mode, the pixel sensor including
- a common junction node,
- a reset transistor having a source connected to the common junction node and a drain receiving an externally supplied power voltage, the reset transistor being gated in response to a reset signal,
- a photo-diode receiving energy externally of the pixel sensor and producing an amount of photo-charge according to the amount of the received energy, the photo-diode converting the produced photo-charge to signal data, the signal data having a voltage level depending on the amount of the produced photo-charge,
- a driving transistor having a gate connected to the common junction node and a drain receiving the external power voltage, and
- a selecting transistor transferring a source voltage of the driving transistor to the data I/O line in response to a first selecting signal;
- a data I/O line carrying the generated signal data and reset data,
- a double sampling circuit coupled to the data I/O line for sampling the signal data and the reset data, and driving an output terminal;
- and
- an output circuit for outputting data related to a voltage level of the output terminal,
- wherein the double sampling circuit samples the signal data before sampling the reset data.
A method for driving an image sensor, including:
- (a) providing CMOS image sensor having a plurality of pixel sensors arranged in rows and columns and that generates reset data during a reset mode and generates signal data depending on an amount of photo-charge produced in response to energy received externally, the method comprising the steps of:
- (b) generating a read signal and activating a row-selecting signal for selecting one of the rows.
- (c) activating a data output signal;
- (d) outputting the signal data in response to the data output signal;
- (e) driving the reset mode after the step (d);
- and
- (f) outputting the reset data.
Dependencies are inferred from the claim text.