Research On CMOS Readout Circuit For IRFPA

Modern infrared (IR) focal plane arrays (FPA) technology has become a advanced comprehensive technologies, including IR material, optics, crygenics, solid-state micromachining technique, microelectronics, and so on. IRFPA plays an important role in military affairs, and can be widely applied in industry and civil fields. IRFPA consist of detector arrays and read-out integrated circuit (ROIC) arrays. CMOS ROIC is becoming a main developing direction of ROIC. ROIC is one of core components in IRFPA. The performances of IRFPA, and even of IR system are directly affected by ROIC. Our country began developing CMOS ROIC in the nineties of the 20th century. And now we are still at starting stage. The performance of our ROIC is much lower than that of West developed countries. Now, it is very urgent to develop IRFPA technology of our own. The subject is supported by the major prepared researching item of "95" national defence(electronic) of the Electronic Ministry and the matched item of minitary industry. In this paper, several typical ROICs , ROIC noise and processing techniques are analyzed systematically in theory, and the computer simulated experiments are done .In the third chapter, many performances are analyzed on typical CMOS ROIC theoretically in detail, such as the non-uniformity, injection efficiency, bias steadiness, frequency characteristic and threshold-voltage non-uniformity. And simulated results are obtained. Then, the same is done on buffered gate modulation input (BGMI) ROIC. BGMI ROIC is a high performance ROIC with adaptive current gain control and background current suppression. It is very significant for surveying far object and high background applications. The simulated results demonstrate that the ROIC structure is correct, and the circuit is helpful for actual BGMI ROIC design later.In the fourth chapter, pyroelectric IRFPA ROIC and Microbolometer IRFPA ROIC are theoretically analyzed. Simulated results are obtained on the two ROIC. Meanwhile, actual testing signals of pyroelectric IRFPA is given.In fifth chapter, IRFPA's noise and noise processing techniques are analyzed, and a new CMOS voltage differential circuit based on current-mode technique is given. The differential, which can be placed in ROIC chip, is used to difference the two voltage signals in CDS in order to reduce fixed pattern noise in ROIC.In the course of researching, we advance and design a on-chip control signals generator based on FPA, and obtain correct simulated result. The circuit of the generator is very simple which can be placed in ROIC chip very easily to reduce alot of the lead line number and volume of ROIC , so as to increase the reliability of the system.