Multi-channel Analogue Front-end Ic Design For Biomedical Signal Acquisitions

With the dramatic development of biomedical engineering and IC technology in recent years, low-noise, low-offset and low-power IC design for biomedical applications has received extensive research interests. Analogue front-end (AFE) IC with the function of signal conditioning is a critical module in the biomedical system. Key issues relating to the design of a high-performance AFE IC, including offset minimization, noise performance and power consumption were investigated in this thesis. Base on the novel design technology, a multi-channel AFE IC design was presented for biomedical signal acquisitions.The new AFE IC consists of low-noise, low-offset preamplifier, current-mode instrumentation amplifier (IA), current-to-voltage converter and voltage/current references. It features of low offset voltage, low noise and high CMRR. Multi-input channel and gain programmable were implemented for different biomedical signals. The non-ideal offset voltage and the noise of the system were improved using a continues-time common-mode feedback (CMFB) offset-cancellation technique. The proposed preamplifier attained a low offset voltage of 80μV, a low input referred noise of 2.1μV at 1Hz while drawing 31.8μW from 1 V voltage supply. In addition, a high sensitive current-to-voltage converter (I-V converter) was employed for accommodating current-mode signal, and the converter rate of it was about 32mV/nA. To resolve the problems in resistors network matching of a conventional IA, a novel current-mode IA with programmable gain was proposed in this thesis. Furthermore, high performance voltage and current references with supply and temperature compensation were designed for the whole system.The proposed AFE IC has been fabricated in SMIC 0.18-μm CMOS 1P6M technology with core area of 1mm2. Experiment results indicated that the input offset voltage was less than 97μV and the CMRR was more than 100 dB, the programmable gain could be set by 0 dB, 30 dB, 50 dB and 70dB. Power dissipation of each analogue channel was approximately 387μW under a 1.8 V single supply voltage. The functions of the AFE IC has been identified by the ECG signal monitoring, experimental results demonstrated that this AFE IC was appropriate for a wide range of biomedical applications.