Development of a Low Noise Multiple Stage Transimpedance Amplifier System For II-VI Quantum Well Infrared Photodetectors

Abstract

Any modern day light detection application requires amplification of the detected signal. So the evolution of amplifier technology is linked closely with advancements made in detector capabilities. Traditional materials used for fabricating Quantum Well Infrared Photodetectors (QWIPs) have given way to newer semiconductor substrates with enhanced physical as well as electrical properties. This along with better fabrication techniques has led to significant performance improvements in infrared (IR) detectors. After Silicon and III-V semiconductors, II-VI heterostructures like ZnCdSe/ZnCdMgSe have been recently explored as promising substrates for developing QWIPs. II-VI detectors have matured to the stage where they can be used to make a commercially viable IR detection system that provides considerable performance enhancements over existing commercial options. Prevailing detectors are integrated with their amplification circuitry so together they can function as an independent module.

Our work focuses on designing and building an amplifier system for II-VI QWIPs with an aim to translate academic research into a consumer-ready product. This is the first time amplifiers have been developed and customized for these detectors. Keeping in mind the salient features of the input photocurrent signal generated from the QWIP, design parameters of the amplifier have been optimized. These include gain, bandwidth, number of stages the gain is cascaded across, frequency response characteristics of each individual stage as well as the entire system, dynamic range, etc. The noise performance of the circuit has been studied for a wide band of operating frequencies and with variations in some design features like gain and active versus passive noise filters. The compact form factor allows for more convenient usability and mobility of the system. We also explore some further possible circuit design optimizations. Our final aim is to develop a customized printed circuit board and external packaging for the detector and amplifier system, and present a working prototype of a commercially feasible module.