自動增益控制應用於陣列式阻抗感測電路

The Application of Automatic Gain Control on Impedance Array Sensing Circuit

吳泓恩(Himith Hongen Wu)

指導教授 ： 孫台平

國立暨南國際大學/科技學院/電機工程學系/碩士(2014年)

摘要

本論文提出一組結合訊號產生模組（Signal Generator Module, SGM）以及自動增益控制（Automatic Gain Control, AGC）之陣列式阻抗感測電路（Impedance Array Sensing Circuit, IASC）架構，以生物阻抗感測作為應用方向進行設計。系統藉由訊號產生模組生成週期感測訊號；由於阻抗感測電路之測量結果受控於感測訊號之振幅，為避免測量結果受到振幅浮動影響，吾人於訊號產生模組與阻抗感測電路間設計自動增益控制電路，以維持感測訊號之振幅大小。吾人並針對自動增益控制電路之增益值對於增益控制之可控範圍與輸出穩定度進行分析，根據分析結果選擇最適於陣列式阻抗感測電路之增益參數。
　　本論文並提出以緩衝放大器注入電路（Buffer Direct Injection, BDI）結合陣列式阻抗感測電路之架構；藉由緩衝放大器注入電路對感測電流進行穩定控制，陣列式阻抗感測電路之輸出線性度得以提升，並增加可測量之阻抗範圍。本論文提出之架構其感測電流標準差為0.024905，輸出電壓之相關係數為0.999601；在感測電流5μA下，此架構之阻抗測量範圍可達10 kΩ至200 kΩ。

關鍵字

訊號產生模組 ； 自動增益控制 ； 緩衝放大器注入 ； 生物阻抗感測

並列摘要

This thesis presents a structure of impedance array sensing circuit (IASC) combined with signal generator module (SGM) and automatic gain control (AGC), which is designed for bioimpedance sensing. Periodic sensing signal generated by signal generator module; since the measuring results of IASC depend on magnitude of sensing signal, to preclude the influence of magnitude floating of sensing signal on measuring results, AGC is designed between SGM and IASC to stabilize the magnitude of sensing signal. The influence of gain of AGC on the controllable range and stability of sensing signal are also analyzed; according to the analysis, parameters favorable to IASC are selected.
To raise the linearity of measuring results of IASC, a structure combined buffer direct injection (BDI) with IASC to stabilize the sensing current is presented simultaneously. With BDI control, the impedance sensing permissible range is also magnified. In this structure, standard deviation of sensing current is 0.024905, correlation coefficient of output is 0.999601, and sensing impedance is able to attain the range between 10 kΩ and 200 kΩ when sensing current is 5μA.

並列關鍵字

Signal Generator Module ； Automatic Gain Control ； Buffer Direct Injection ； Bio-impedance Sensing

參考文獻

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