宽频带电容层析成像系统模拟前端

Analog Front-End for Wideband Electrical Capacitance Tomography System

摘要

宽频带电容层析成像(ECT)是实现工业多相流可视化监测的关键技术之一. 跨阻放大器(TIA)是电容层析成像系统模拟前端中的重要部件，其性能直接影响系统的最大带宽与分辨率. 然而，传统的跨阻放大器的带宽、增益严重受限于同轴线缆和电路板寄生电容的影响，在高频、高增益情况下极易出现稳定性问题. 针对该问题，基于低成本商用器件设计了新型隔离 T 形反馈跨阻放大器，对寄生电容进行隔离，提高跨阻放大器模拟前端的高频稳定性. 实验结果表明，新型跨阻放大器在 54 dBΩ 的增益下，具有 684.63 MHz 的高带宽和 1.96 μA 的电流分辨率，并且能保持 45°的相位裕度，满足电容层析成像系统的宽频带微弱电流的测量需求，较好地解决了高频稳定性问题.

Abstract

Wideband electrical capacitance tomography(ECT)is a key visualization technique for industrial multi-phase flow detection. The transimpedance amplifier(TIA)is an essential component of the analog front-end in ECT systems，and its performance directly affects the system's maximum bandwidth and resolution. However，the transimpedance bandwidth and gain of a traditional TIA are limited by the parasitic capacitance introduced by the coaxial cable and printed circuit board(PCB)trace. These parasitic components may cause resonance in a high-frequency or high-gain configuration. Based on low-cost commercial devices，a novel isolated T-feedback TIA was proposed to isolate the parasitic components，thereby enhancing high-frequency stability of the TIA analog front-end. The experimental results show that the proposed TIA achieves a high bandwidth of 684.63 MHz and a current resolution of 1.96 μA at a gain of 54 dBΩ，while maintaining a phase margin of 45°. The proposed TIA can meet the measurement requirements for wideband weak currents in an ECT system and effectively solve the problem of high-frequency stability.

关键词

宽频带电容层析成像 / I/V 转换器 / 跨阻放大器

Key words

wideband electrical capacitance tomography / I/V converter / transimpedance amplifier

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基金资助

国家自然科学基金资助项目(61973232)