Wide-Bandwidth Low-Noise Simple Differential Transimpedance Amplifier Ideal for Detecting High-Frequency Faint Optical Signals

Transimpedance amplifiers (TIAs) are core components of faint optical signal detection. This paper proposes a differential TIA with low noise, low cost, high sensitivity and a simple structure. Compared with typical TIAs, the TIA utilizes only one operational amplifier (op-amp) for differential amplification, effectively eliminating DC bias and reducing both intrinsic and external noise. This feature renders the TIA exceptionally suitable for the detection of high-frequency faint optical signals. The TIA maintains a wide bandwidth while eliminating the noise and errors caused by the reverse bias of photodiodes (PDs). When integrated into fiber optic gyros (FOGs), the TIA can suppress electronic crosstalk noise, thereby enhancing accuracy and reducing the dead zone of FOGs. The gain bandwidth product of the TIA is approximately 140 GHz·Ω with a single AD8065 op-amp and approximately 600 GHz·Ω with a single OPA847 op-amp. In this paper, a T-type capacitive network is applied instead of a T-type resistive network to suppress the adverse effect of parasitic capacitances. This paper also provides a specific solution for noise reduction of the light source in FOGs utilizing the TIA, which effectively improves the detection accuracy and bias stability of FOGs.