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为了符合低功耗的绿色环保理念,设计实现了可检测微弱心电、脑电信号的低功耗CMOS模拟前端集成电路.电路系统包含低噪声放大器、开关电容型增益可调放大器和逐次逼近型模数转换器(SAR ADC)等模块.低噪声放大器采用全差分Rail-to-Rail运放作为主体结构,代替了传统仪表放大器;增益可调放大器通过开关电容网络实现4种可调增益.与传统前端电路相比,设计中增加了片上SAR ADC模块,改善了现有前端电路多采用模拟输出的不足.电路基于GSMC 0.18 μm CMOS工艺进行设计,采用Cadence Spectre工具完成仿真.仿真结果表明,在1.8V电源电压下,前端电路整体功耗为115.6 μW,能够实现准确的数字输出.“,”In order to comply with the concept of green environmental protection,a low power CMOS analog front-end integrated circuit for weak signal detection was introduced.The integrated circuit system contained a low noise amplifier,a programmable gain amplifier with switching capacitors,a successive approximation analog to digital converter (SAR ADC) and other modules.Instead of the traditional instrumentation amplifier,a fully differential rail-to-rail operational amplifier was used as the main structure of the low noise amplifier.In the programmable gain amplifier,a differential folded cascode operational amplifier and a switch capacitor network were used to achieve 4 kinds of adjustable gain.In addition,compared with the traditional front-end circuit,an on-chip SAR ADC was added to overcome the shortcoming of analog output appeared in the front-end circuit nowadays.The proposed circuit was designed in GSMC 0.18 μm CMOS process,and was simulated by Cadence Spectre.The simulation results showed that the whole power consumption of front-end circuit was 115.6 μW at a power supply voltage of 1.8 V.The circuit could achieve accurate digital output.