A High Input Impedance AFE IC for Multi-channel Fetal ECG Detection with Dry Electrode

As fetal electrocardiographic (fECG) monitoring plays a crucial role in non-invasive prenatal diagnosis, the demand for accurate and reliable fECG acquisition systems is increasing. The dry electrode provides an ideal solution for the wearable fECG monitoring system design. However, input impedance matching and common-mode noise rejection remain significant challenges in the practical implementation of dry electrodes. This paper presents an analog front-end (AFE) integrated circuit specifically aimed at improving the quality of fECG signals detected by the wearable system with dry electrodes. The AFE utilizes bootstrapping circuits and an instrumentation amplifier to achieve high accuracy and stability. A driven-right-leg circuit is incorporated to effectively suppress electromagnetic interference. The AFE is designed and verified using 180 nm CMOS technology. The results demonstrate a high input impedance of 319 GΩ and a high CMRR of 106 dB. Furthermore, the proposed design offers a suitable gain, low power consumption, and high reliability, making it a promising solution for fECG monitoring with dry electrodes.