生理信号采集的多通道CMOS模拟前端集成电路设计

1 Introduction
In recent years, healthcare technologies are increasingly important and have received extensive research interests [1, 2]. Since most physiological signals exhibit relative weak signal strength and low frequency (as listed in TABLE I [3, 4]), the front-end IC design is fundamentally crucial. To accommodate different physiological signals and reproduce the signal in the digital domain, a multi-channel front-end IC with lowoffset gain programmable instrumentation amplifier (GPIA) and ADC should be elaborated. In addition, a high sensitive current-to-voltage converter (I-V converter) is desired for accommodating current-mode signal, such as the current output from a photodiode used for photoplethymograph (PPG) measurements.
包含增益可调仪表运算放大器、高灵敏度电流-电压转换器、基准源以及8位逐次逼近式模数转换器(SAR ADC)。为适应不
同种生理信号的采集，该集成电路具有可配置特点。整个芯片采用SMIC混合信号0.18-μm CMOS 1P6M工艺制作，核心电 路的芯片面积为1.36 mm2。芯片测试结果显示：该芯片在1.8V单电源供电电压下输入失调电压小于97μV，可调增益范围
为30dB 至70dB，其中ADC的微分非线性(DNL)和积分非线性(INL)分别为-1/+1.4 LSB、-2/+2 LSB。增益可调仪表运算放大
器以及ADC工作在采样率250kS/s的功耗分别是387μW和704μW。该模拟前端集成电路可以适用于较低幅度、低频率生物
医学信号的采集。
关键词 生物医学电路与系统；模拟前端；多通道； 生理信号采集
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Vol. 3 No.9 / Sep. 2009
Multi-Channel CMOS Front-End IC for Physiological Signal Acquisition
生理信号采集的多通道CMOS模拟前端集成电 路设计பைடு நூலகம்
张金勇 王磊 于力
ABSTRACT A compacted and low-offset multi-channel CMOS front-end IC for physiological signal acquisitions is presented in this paper. The proposed mixed signal IC includes low-offset gain programmable instrumentation amplifiers, high sensitive current-to-voltage converters, voltage/current reference and analog-to-digital converter (ADC). To make the IC adaptive to different physiological signals, the gain of the IA is configurable. The ASIC was fabricated using SMIC 0.18-μm CMOS 1P6M technology. Experiment results indicated that the input offset voltage was less than 97 μV and the CMRR was more than 100 dB. Operating in 8-bit mode, the ADC exhibited -1/+1.4 LSB DNL and -2/+2 LSB INL, respectively. Power dissipations of each analogue channel and the ADC were approximately 387 μW and 704 μW under a 1.8 V single supply voltage, respectively. It is suitable for a wide range of high precision biomedical applications.
KEYWORDS Biomedical circuits and systems; analog front-end; multi-channel probe; low-offset; biomedical signal acquisition
摘 要 本本文提出并设计了一款基于生理信号采集的低失调全集成多通道模拟前端集成电路(IC)。该混合信号集成电路
to digitize the amplified signals from channels at the appropriate sampling rate. Finally, a novel high precision current/ voltage reference was presented in this design. A bias generator and a built-in digital control circuit were exploited to generate the bias currents and gain select signals for the front-end IC.
Frequency Range
DC-150 Hz DC-50 Hz DC-1 Hz 0.01-250 Hz DC-500 Hz 0.05-40 Hz
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生理信号采集的多通道CMOS模拟前端集成电路设计
provide enough CMRR and low-offset performance.
and a resolution of 8-bit SAR ADC was integrated
Table I. Properties of several physiological signals
Physiological Signals EEG ERG EGG ECG EMG PPG
Measurement Range
25-300 ȝV 5-900 ȝV 10-1000 ȝV 0.5-4 mV 0.1-5 mV 5-100 nA
In this paper, we proposed a multi-channel configurable physiological signal acquisition front-end IC with lowoffset voltage, where a high sensitive I-V converter and an 8-bit successive-approximation register (SAR) type ADC were integrated and the gain of the system is configurable. This initial version of the system was