Research Of Nb₅N₆Microbolometer Readout Circuit

In recent years, Terahertz (THz) irradiation has attracted much attention and effort in its research, for reasons of its outstanding performance and great promise in practical applications in such areas as physics, astronomy, biology and information science, and consequently, THz detectors is the focus of most THz researches. Because Nb5N6room temperature Microbolometer has a high response to THz irradiation, Nb5N6Microbolometer has great advantages in terms of THz detection and THz imaging, because of its capabilities of working in room temperature, low noise and ease of fabricating large scale arrays, in comparison with other THz detecting systems.This thesis designed a single-channel low noise readout circuit consisting of such circuit modules as impedance transformation, DC block, low noise amplifier and low pass filter, after studying and analyzing such performance indexes of room temperature Nb5N6Microbolometer as its response to THz signals, noise characteristics and response time. Because of the high output impedance of Nb5N6Microbolometer, the readout circuit is designed to have a high input impedance in the order of MQ., through the design of impedance transformation circuit. The DC block and amplification circuit not only filter out the relatively strong DC component of the output signal, but also amplify the AC component by59.5dB. The circuit has outstanding noise performance. Its noise spectrum density is approximately10nV/Hz1/2at the frequency of around1.5kHz. Moreover, the passband of the circuit ranges from228Hz to3.703kHz, and has a stable amplification of the response signals with different amplitudes. The circuit can amplify response signals as low as200nV.The circuit realizes selected readout of16channels of Microbolometer signals, by utilizing the application system based on Atmel AT89S52to control the multiplexer ADG506A, on basis of single-channel readout circuit. Finally, we have made a16-channel low noise readout circuit.