A Modified Regulated Cascode transimpedance amplifier with extra feed-forward path to enhance gain and bandwidth

This paper presents a transimpedance amplifier (tia) for high sensitivity near infrared spectroscopy (nirs). the proposed tia is based on the regulated cascode (rgc) structure with an extra transistor employed to implement additional feed-forward path and achieve higher gain values. the extra transistor senses a partially amplified input signal, available in the conventional circuit, and conveys an additional ac current into the load, which provides a higher gain. in addition, a bandwidth extension method is introduced using a capacitor and resistor, which can improve amplifier’s bandwidth by 40%. the proposed tia is designed in 0.18µm cmos technology and achieves a transimpedance gain of 101.9db with a -3db bandwidth of 91.2 mhz considering 2pf of photodiode capacitance at the tia input. the input referred noise is 4.4pa/√hz while dissipating 151µw power.