Digital Calibration Method for Analog-to-Digital Converter of High Performance CMOS Image Sensor Array

Abstract

The invention belongs to the field of semiconductor image sensing, and in particular relates to a digital correction method for a high-performance CMOS image sensor array analog-to-digital converter. The invention proposes an algorithm based on multi-channel cooperative digital correction technology, especially for the characteristics of a large number of ADCs in a CIS array ADC, a very small area of ​​a single ADC, and a large capacitance mismatch. Array of analog-to-digital converters for CIS sensors. The overall design uses a low operating voltage of 1.8V. The pixel voltage output of the image sensor is directly sent to the analog-to-digital converter (ADC) array after being converted by the variable gain amplifier (VGA) array, and then sent to the digital correction engine for calculation, which will be applied to the array analog-to-digital converter of the CMOS image sensor Forming an overall system greatly reduces the mismatch problem of the array ADC due to the small area of ​​a single ADC. The multi-channel cooperative digital correction technology applied to the array analog-to-digital converter of the image sensor proposed by the present invention can effectively improve the overall performance of the array analog-to-digital converter.

Description

technical field [0001] The invention belongs to the field of semiconductor image sensing, and in particular relates to a multi-channel cooperative digital correction method for an array analog-to-digital converter chip of a high-performance CMOS image sensor. Background technique [0002] In recent years, CMOS image sensors (CIS) have achieved great success in consumer electronics and professional fields, and have basically replaced traditional CCD image sensors except for very special applications. CIS integrates an analog-to-digital converter (ADC) array on chip, which helps to improve system integration, enhance signal-to-noise ratio and signal anti-interference ability. At present, people put forward higher requirements for CIS, mainly focusing on the following three aspects: [0003] (1) High resolution. The early CIS resolution was VGA (640×480) level; currently, the mainstream HDTV (1080p) requires a single-chip color CIS resolution to reach 9 million pixels, and th...

AI Technical Summary

Problems solved by technology

Although the traditional SAR ADC also needs N operations to get the final conversion result, its power consumption has a very large advantage, which is very important for CIS chips that integrate thousands of ADCs internally.

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