A 79 dBΩ 1.2 GHz Low-Noise Single-Ended CMOS Transimpedance Amplifier for High-Performance OTDR Applications

Agata Romanova, Vaidotas Barzdenas


The paper discusses the design methodology for a low-cost high-gain CMOS transimpedance amplifier for optical time-domain reflectometers. The circuit is implemented using 0.18 µm CMOS technology and employs a noise-efficient capacitive feedback structure to address the noise problem of conventional design approaches such as feed-forward or resistive feedback architectures. The simulation results show a gain of 82/79 dBΩ with 3-dB bandwidth of 1.2 GHz and average input-referred noise current density below 1.8 pA/sqrt(Hz) in the presence of a 0.7 pF total input capacitance. The circuit including the output buffer consumes around 21 mW while running from 1.8 V power supply. Several circuit-level modifications to the reference topology are introduced to address the issues such as DC current elimination, voltage headroom problems and typical parasitic capacitances in commercial CMOS technology.


Analog integrated circuits; Broadband amplifiers; CMOS integrated circuits; Optical time-domain reflectometry, Transimpedance amplifier

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