Abstract
In modern clinical practice, monitoring of biomedical signals is a crucial and important part. The biomedical signals most commonly used in medical diagnoses include EEG, ECG and EMG, etc. Therefore, there is a growing demand for small-size portable biomedical signal acquisition systems to improve the patients’ quality of life. The low noise biomedical signal readout frond-end consists of a chopper current-balancing instrumentation amplifier (CCBIA), a small Gm-C low pass filter, and a programmable gain amplifier. The CCBIA utilizes the chopper stabilization to reduce the flicker noise and amplifiers the low amplitude biomedical signals. The common mode rejection ratio (CMRR) is also the important specification because there are Electromagnetic Interference (EMI) and Electrostatic Field Interference (EFI) when measuring biomedical signals. Behind the CCBIA, a low-pass filter is needed to reduce the out-of-band noise higher than the biomedical signal of interest, and the programmable gain amplifier is used to avoid the output signal to be saturated. The analog ECG motion artifact detector is proposed to save the power consumption of motion artifact reduction in DSP. The article is fabricated by TSMC 90nm CMOS process. The measurement results shows that the readout frond-end achieves 107dB CMRR, the gain and the bandwidth are tunable for EEG and ECG, integrated input-referred noises are only 1.06 μVrms and 1.64 μVrms within EEG and ECG signal bandwidth. The ECG motion artifact analog detector can detect the skin-electrode impedance variation and the ECG signal variation successfully. The total power consumption is 22.17 μW.