A low-power noise scalable instrumentation amplifier for fetal monitoring applications

This paper proposes a low-power noise scalable instrumentation amplifier (IA) for fetal monitoring applications. The noise specification of the IA is made adaptive to the peak-peak value of the fetal electrocardiography (fECG) signal, which varies for different gestational age and measurement settings. Contrary to the currently available point solution IAs, the proposed IA is scalable for a noise range from 30nV/VHz to 250nV/VHz while consuming 15μW to 1μW respectively. A new IA architecture is proposed to achieve a better noise efficiency factor (NEF), while allowing noise scalability. The IA is designed in TSMC 0.18μm CMOS process. Simulation results show that the IA achieves a NEF of 3.4 to 5.5 over the noise scalable range, a CMRR of 100dB, and an input impedance (Zin) of 1GO.