Su Bo, Yang Xue, Cui Hailin, Jones David R
Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Beijing Advanced Innovation Centre for Imaging Theory and Technology, Department of Physics, Capital Normal University, Beijing 100048, China.
Rev Sci Instrum. 2022 Apr 1;93(4):043004. doi: 10.1063/5.0079747.
The bandwidth of very high gain (≥100 MV/A) transimpedance amplifiers is restricted to below 100 kHz, unless measures are employed to mitigate the effect of circuit parasitic capacitances. Current approaches involve significantly increased circuit complexity and component count. They may suffer unwanted noise pickup or destructive capacitive coupling to ground, the latter restricting the available bandwidth. We demonstrate that combining a positive feedback circuit with a low-pass filter network extends the bandwidth of a transimpedance amplifier out to the limit of gain peaking (>1 MHz) without increasing the noise signal. The circuit uses a single inverting amplifier and very large feedback-resistance to provide a canceling parasitic-capacitance positive feedback signal. This can negate both the negative feedback-resistor parasitic-capacitance and the input/output pin parasitic-capacitance of the transimpedance amplifier. The circuit solves the problem of destructive distributed-capacitive coupling to ground along the feedback resistor.
极高增益（≥100 MV/A）的互阻放大器的带宽被限制在100 kHz以下，除非采取措施减轻电路寄生电容的影响。目前的方法会显著增加电路复杂性和元件数量。它们可能会受到不必要的噪声拾取或与地的破坏性电容耦合，后者限制了可用带宽。我们证明，将正反馈电路与低通滤波器网络相结合，可以将互阻放大器的带宽扩展到增益峰值极限（>1 MHz），而不会增加噪声信号。该电路使用单个反相放大器和非常大的反馈电阻来提供抵消寄生电容的正反馈信号。这可以消除互阻放大器的负反馈电阻寄生电容和输入/输出引脚寄生电容。该电路解决了沿反馈电阻与地的破坏性分布电容耦合问题。
