Analog-to-digital converter and controlling method thereof

Abstract

An A / D converter consists of sampling holder, A / D converting circuit, reference voltage source, correction-coding circuit, clock generating circuit and various grades of sub circuits. It is featured as controlling programmable gain amplifier and controllable voltage source by output control signal according to data collected by image transducer for raising image quality.

Description

technical field [0001] The invention relates to the technical field of integrated circuit design of microelectronics, in particular to an analog-to-digital converter for a CMOS image sensor and a control method thereof. Background technique [0002] At present, digital processing technology is developing vigorously, but all existing in nature are analog signals, so ADCs that convert analog signals into digital signals are widely used. For example, in a digital camera, the image sensor converts the light signal into an analog electrical signal, and then an ADC is required to convert the analog electrical signal into a digital signal for processing by a digital image processor. [0003] Commonly used ADCs can be divided into full-parallel ADCs, semi-parallel ADCs, interpolation ADCs, and Σ-ΔADCs and pipeline ADCs according to their structures. The conversion speed of full-parallel ADC, semi-parallel ADC, and interpolation ADC is very high, but the conversion accuracy is low. ...

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Problems solved by technology

Similarly, the output level of the CDS varies greatly with the change of the scene. The reference voltage source 105 provides a fixed voltage, which cannot be consistent with the CDS output in various scenes, thereby affecting the dynamic range of the image sensor output and affecting the image quality.

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