- 學位論文
心電圖儀中電壓式濾波電路之改良
Improvement of Voltage-Mode Filter Structures in Cardiograph
摘要
摘 要 隨著社會漸漸邁入高齡化社會，電子醫療監測器材逐漸被受到發展與重視。但擷取生理訊號是非常微弱的，也容易被受測者本身、量測環境及設備等因素所影響，故類比濾波電路的性能與準確度是相當重要的研究。 本論文主要是改良心電圖儀中之類比濾波電路的性能與準確度，在過去通常都用運算放大器(Operational Amplifier)為主動元件來進行設計，為改良其性能與準確度，本論文使用運算轉導放大器(OTA)為主動元件來設計濾波電路，具有以下優點：(1)使用單端輸入的OTA(可免除寄生電容的Feed-through效應)，(2)使用接地電容(可直接吸收寄生電容)，(3)所有外加電容位置恰好與所有寄生電容的位置相同，吸收了寄生電容，並減少寄生效應對整體電路的影響。 在改良電路上，使用運算轉導放大器(OTA)，配合電容器設計成一個單輸入單輸出最少主被動元件的電壓式N階萬用濾波電路，並將結果與OA電路比較，在150Hz低通濾波部分：使用四階OTA電路，f3db準確度誤差從3.95％降低至0.01％，衰減斜率從-1.872加大至-3.335。在0.05Hz高通濾波部分：使用四階OTA電路，f3db準確度誤差從5.24％降低至0.37％，衰減斜率從1.619加大至3.466。並在60Hz帶拒濾波部分：使用十階OTA電路，中心頻率準確度誤差維持在0.23％，頻帶寬度從24.41Hz~142.39Hz縮減至51.83Hz~68.76Hz，大幅改進其濾波電路之性能。 最後，本論文以H-spice軟體進行電路模擬，OTA電路製程參數為TSMC035μm，OA電路元件參數為LM 741，並將改良前後之濾波電路模擬結果予以比較。
並列摘要
Abstract As society gradually enter the aging society, the devices of electronic medical monitor was most notably playing a major role in the society. As a matter of fact, it was very weakly to get of the biomedical signal message. The mood of patient and environment can affects on the measuring performance. So, it is true that study of analog filter circuit by performance and accuracy. The study improved the performance and accuracy by analog filter circuit. In the past, it is designs by the operational amplifier to the active components. The study using the actively material of to design the filter circuit in order to improve the performance and the accurate: (1) using single-ended-input OTAs (overcoming the feed-through effect due to the use of differential-input OTAs), (2) using grounded capacitors (absorbing the shunt parasitic capacitance), and, (3) using the minimum components and all the parasitic capacitances have the same places as those of all the given capacitors in the realized circuits. On the improvement circuit, using the OTAs, the capacitance role of design a single-ended-input single-ended-Output minimum active and passive components is voltage-mode N-order universal structures and compare the result with OA circuit. In 150Hz Low-Pass Filter section: using the OTA circuit by 4-order. The accuracy result is that f3db is error form 3.95% to 0.01％. The reduce slope is largest from -1.872 to -3.335. In 0.05Hz High-Pass Filter section: using the OTA circuit by 4-order. The accuracy results is that f3db is error form 5.24% to 0.37%. The reduce slope is largest from 1.619 to 3.466. In 60Hz Notch filter section: using the OTA circuit by 10-order. There of accuracy by center frequency maintain the performance on 0.23%. The band-wide is lower from 24.41Hz~142.39Hz to 51.83Hz~68.76Hz. The results are a great improvement the performance of filter circuit. Finally, the project is proceeding simulate by the H-spice. The OTA circuit of demonstrate parameter by TSMC035μm. The OA circuit material of parameter by LM 741, and the finally results will compare around the improving.