Wide-bandwidth low-noise simple-structured differential transimpedance amplifier ideal for fiber optic gyros

Abstract This paper proposes a simple-structured (single-op-amp) differential transimpedance amplifier (sdTIA) characterized by wide bandwidth, low noise, and high sensitivity. Compared with typical TIAs, the sdTIA employs only one operational amplifier for differential amplification, effectively eliminating DC bias and reducing noise. It maintains a wide bandwidth while eliminating the noise and errors caused by reverse bias of the photodiode. Upon experimental validation, the sdTIA reduces noise voltage to below 10% of the original, enhancing the signal-to-noise ratio by more than 20 dB. This feature makes the sdTIA exceptionally suitable for detecting high-frequency faint optical signals. The gain-bandwidth product of the sdTIA is approximately 140 GHz ⋅ Ω with a single AD8065 operational amplifier, and approximately 500 GHz ⋅ Ω with a single OPA847 operational amplifier. To suppress the adverse effects of parasitic capacitance, a T-type capacitive network replaces the T-type resistive network within the sdTIA, avoiding additional noise. When integrated into fiber optic gyros (FOGs), the sdTIA can suppress electronic crosstalk noise, thereby enhancing accuracy, stability, and reducing the dead zone. Based on it, this paper provides a specific solution for noise reduction of the light source in FOGs. The sdTIA can also be used in other high-sensitivity photoelectric transducer applications, such as optical tomography and optical biosensors, only with appropriate adjustments to the bandwidth and gain.