CMOS image sensor brief discuss
From;    Author:Stand originally

Digital camera and can take a picture type of portable apparatus arisen, make this noun enters CMOS image sensor popular eye shot, and this kind of product also became a the growth in semiconductor product is the rapiddest kind. Actually, before a few years, CMOS sensor still does not have so dazzling today position, in those days it still can look up at powerful adversary CCD sensor only. But, it is kongfu of a few years merely, it is OK be the same as CCD stand up to sb as an equal.

With the contrast of CCD


CCD (Charge Couple Device) formal name calls charge coupling parts of an apparatus, it is the array parts of an apparatus that a kind of photoemission that used semiconductor changes smooth signal. In CCD, after the smooth signal course that every unit feeling gets delivers collect, unite again change into telegraphic date. Its image distortion factor is inferior, it is high end all the time the first selection of video product. But, CCD also has his drawback, because signal is ordinal in unit,deliver, with respect to need exterior and accurate clock generator and drive circuit close suitably, the result causes the accretion of product volume and power comsumption.


The basic and sensitive principle of CMOS and CCD are identical, nevertheless its make craft and structure and CCD very different. The name origin of CMOS its workmanship, this is the current technology of industry of a kind of semiconductor, can be in consequently same base piece on compositive sequential, control and signal processing circuit, reduced cost greatly. In CMOS sensor, the smooth signal that every unit induction goes to can reach ADC to convey directly by adjacent amplifier in memory. Nevertheless, leakage current is a its inherent blemish, the picture quality that brings about from this drops is the enormous challenge that its face all the time for years.


In comparative for some time inside, both became high-grade with general delegate. Nevertheless, the thing is not had absolutely, as the progress of CMOS craft, both the distance between is shortening stage by stage. Because CMOS craft is advancing all the time, the problem of leakage current also is in get ameliorative stage by stage, and its are low the tradition of power comsumption also got acceding. Newest CMOS product, the CMOS image sensor of for example Micron, its had been achieved like element resolution breathtaking 10 million like element, this kind of simple change makes the antenna of CMOS sensor has begun to enter the traditional field that CCD place holds.

The requirement of the market


What does the market have to ask to image sensor? Actually like the requirement to other semiconductor product, it is muti_function case of compositive, low, still have property of course. Nevertheless, this 3 person between should reach a kind of equilibrium, to compositive manufacturer pays close attention to spend the requirement with cost most. Can see from above paragraphs, CMOS image sensor is close to these two requirements most. CMOS craft agrees with manufacturing number chip, this gives image sensor compositive DSP brought natural convenience condition, plus the ADC that is together originally, processing system of image of a number shaped. Cite a case, the MT9V131 of Micron is a typical case, it is a 1/4 inch sensor of VGA CMOS image, compositive but process designing processor and 10 ADC, data rate is 1200 ~ 1350mpix/s, dynamic limits can amount to 60dB. Similar product still has the OV7141-C01A of OmniVision, the ADCC-3960 of Avago. Because,also be of these products appear, made CMOS image sensor receive wider application.
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