應用於ECG生醫訊號檢測之類比前端可調式增益放大器;A Programmable Analog Front-End Amplifier for ECG Biomedical Signal Detection

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/90299

Title:	應用於ECG生醫訊號檢測之類比前端可調式增益放大器;A Programmable Analog Front-End Amplifier for ECG Biomedical Signal Detection
Authors:	鄭力瑜 Cheng, Li-Yu
Contributors:	電機工程學系
Keywords:	類比前端低雜訊放大器;虛擬電阻;電流重複利用;Analog Front-end Amplifier;Pseudo Resistor;Current Reusing
Date:	2022-08-17
Issue Date:	2022-10-04 13:39:38 (UTC+8)
Publisher:	國立中央大學
Abstract:	隨著近期健康樂活的觀念抬頭和高齡化社會的影響，人們越來越重視健康保健的重要性。科技的演進以及健康的保衛使生醫電子領域逐漸受到重視，穿戴式裝置產業也因此而興盛。穿戴式裝置提供民眾即時的醫療監控，在運動當下可透過裝置取得自身心跳、壓力、肌力等數據，並利用無線傳輸技術將資訊同步至行動裝置中。由於生理訊號相當微小，在穿戴式裝置中如何不受雜訊影響則成為重要的課題，本電路以生醫醫療為出發點，低功耗、低雜訊為開發指標，期許研究成果能對社會大眾福祉有所助益。本論文實現應用於ECG 生理訊號之生醫類比前端可調式放大器，並分為低雜訊放大器(LNA)以及可調增益放大器(PGA)兩個部分，系統架構採用電容耦合式儀表放大器 (CCIA)以阻絕電極貼片端所產生的直流偏移。電路架構採用電流重複使用技術(Current- Reusing)使相同電流下擁有兩倍的轉導值，提高電流使用效率(gm/Id )，實現生醫晶片低功耗、低雜訊之訴求。而透過頻譜分析可推估心電訊號(ECG)的頻率大約為0.5~200 Hz，本作品使用虛擬電阻(Pseudo Resistor)提供的高阻值達到電路對低頻的訊號擷取，並採用源極退化(Source Degeneration)使電路擁有更高的相位餘裕和線性度以利後級A/D 訊號處理。PGA 電路則是利用開關的切換得到不同的電容比值，可根據生理訊號的不同振幅做相應的增益調控。本電路採用台積電0.18μm CMOS 1P6M 製程，晶片面積約佔0.72 mm2，電源供應電壓為1.2V，整體電路功耗為1.495 μW，電路頻寬為0.5~200 Hz。透過可調增益放大器後分別可得到54 dB、48 dB、42 dB 之增益，應用頻寬內輸入雜訊為0.45 μVrms，雜訊效率因子(Noise Efficient Factor)為1.69。;With the impact of the aging society and the growing conscience of healthy life, people are paying more attention to the health care. As technology is progressing as well as the awareness of health care, biological electrical field has become increasingly important in recent years. Wearable devices, due to this, are used a lot more. Provided with a real-time medical monitor, people can gain information of their heart beat rates, heart pressure and muscle condition while exercising. Given that the biological signal is tiny, it is worth discussing how to decrease the influence of noise on these wearable devices. The proposed circuit that is based on biomedical usage sets low power consumption and low noise as its development targets, which are indicators that can benefit the world. This thesis presents a design of programmable analog front-end amplifier for ECG biomedical signal detection and is composed of low noise amplifier (LNA) and programmable gain amplifier (PGA). Capacitor-coupled instrumentation amplifier (CCIA) architecture is applied to both parts for rejecting DC offset of front-end electrode-tissue. The current-reusing technique is used for twice transconductance with same current, which let MOSFETs operate with high gm/Id ratio and meet the demands of biomedical circuit for low-power and lownoise . We can estimate the bandwidth of ECG signal from database is about 0.5 to 200 Hz by spectrum analysis. Using the high impedance from pseudo resistor, the proposed circuit manage to capture the extremely low-frequency of ECG signal. Source degeneration design technique is adopted to have more phase margin and linearity in the proposed circuit, which makes output signal performance better in total harmonic distortion. The switched are used in PGA circuit to obtain different capacitance ratio, for adjusting the gain according to the different amplitudes of the biological signal. These circuits are designed in TSMC 0.18 μm CMOS 1P6M process and the chip area is 0.85 mm2. The power consumption is 1.495 μW for 1.2 V power supply voltage. The iii minimum low cut-off frequency is 0.5 Hz and application bandwidth is 200 Hz. With PGA, the system gain can be 54 dB, 48 dB, 42 dB respectively. Finally, input-referred noise is 0.45 μVrms and noise efficiency factor (NEF) is 1.69.
Appears in Collections:	[Graduate Institute of Electrical Engineering] Electronic Thesis & Dissertation

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