Design Of ROIC In Infrared Detector Based On CTIA Structure

Nowadays, the IR imaging system application is getting more and morewidespread. And, related to astronomy, medicine, military, meteorology, materialappraisal, data transfer and other aspects. the IR imaging system can help in severalforms such as disaster rescue, night vision, homing and tracking, ecology and weatherforecasting, target acquisition, predictive inspection and maintenance, surveillance,short range communication, remote temperature sensing, spectroscopy and medicaldiagnostic and treatment. In particular, images produced with that radiation is calledthermograms.First of all, the article introduces the infrared detectors. Then, briefly discussesthe performance of the readout circuit, the basic structure of the readout circuit(ROIC). The design of the entire circuit including: the integration circuit, thesample-and-hold circuit, the buffer circuit, the bias circuit, the row control circuit, acolumn control circuit and a digital logic control circuit. The main results wereobtained as follows:(1) In order to provide a stable bias voltage to the detector, the main structure ofthe readout circuit has used the capacitive feedback cross amplifier structure. In orderto reduce overall power consumption, the amplifier of CTIA(capacitivetrans-impedance amplifier) has used the simple difference input amplifier structure.Through to the simulation of circuit, the power consumption of overall circuit is77.8mW.(2) The noise of circuit mainly includes following several aspects: shot noise,reset noise and the readout noise. In order to reduce the noise in the circuit, the sampleand hold circuit uses a correlated double sampling structure. Under the conditions ofthe bandwidth of1GHz and T=300K, the simulation result of the total output noise is0.0312V. (3) This work designed a ROIC (read out integrated circuit) of a320×240FPA(the focal plane array) in0.35μm n-well CMOS process. The signal output timeof each line is41.66μs, and the circuit has240lines. The image output time is10ms/frame, therefore the output speed is100frame/s. At the same time, the outputlinearity of the circuit can reach99％.