REFERENCE VOLTAGE GENERATOR, COLUMN ANALOG TO DIGITAL CONVERSION DEVICE, AND IMAGE CENSOR FOR ELIMINATING POWER SUPPLY AND SWITCHING NOISE IN IMAGE SENSOR, AND METHOD THEREOF

摘要

A reference voltage generator of an image sensor, a column analog-to-digital converter, an image sensor, and a column analog-to-digital conversion method for eliminating power supplied to a pixel array and switching noise are provided to cancel a noise component in an active correlated double sampling operation by using a noise replica reference voltage to achieve an analog-to-digital conversion operation robust to noise. A column analog-digital converter includes a reference voltage generator(150) and an active correlated double sampling circuit(132,134,136). The reference voltage generator generates a correlated-double-sampled OB(Optical Black) sampling signal from an OB pixel output signal in response to the OB pixel output signal and a first lamp signal and generates a second reference voltage based on the OB sampling signal and a first reference voltage. The active correlated double sampling circuit generates a correlated-double-sampled active sampling signal from an active pixel output signal in response to the active pixel output signal and a second lamp signal and compares the active sampling signal with the second reference voltage to generate a signal for generating a digital code.