High-gain transimpedance amplifier design for high-responsivity photodetector microcurrent detection

This paper investigates a signal amplification circuit for laser warning systems, where microcurrent pulses generated by a PIN-type (InGaAs) photodiode are converted into voltages using a transimpedance amplifier (TIA). Theoretical analysis of the TIA gain is presented and validated through simulation. Results demonstrate a highly linear relationship between photodiode output current and TIA output voltage across all laser power levels. In addition, a field-effect transistor (FET)- based operational amplifier is characterized, and two photodiode amplifier configurations are compared: a conventional TIA topology and a resistive-tee network. Experimental findings confirm that the resistive-tee network improves circuit performance, offering enhanced detection capability for PIN-type (InGaAs) photodiodes.