A 12.3-μW 0.72-mm² Fully Integrated Front-End IC for Arterial Pulse Waveform and ExG Recording

Abstract

In this article, a power and area efficient front-end (FE) IC for biomedical instrumentation is presented. In addition to ExG recording, the proposed system provides a noninvasive arterial pulse waveform (APW) detection through direct skin contact with a packaged silicone-coated resistive-bridge pressure sensor. An automatic calibration technique is proposed to compensate for the resistive-bridge offset and reduce it down to 1 mV. High linearity in the FE is provided through the use of an instrumentation amplifier (IA) with a super class-AB output stage. The IA is followed by a single block for programmable gain amplification (PGA), low pass filtering (LPF), and analog-to-digital converter (ADC) functionality. The PGA-LPF-ADC has a reconfigurable gain from 6 to 14 dB and can cover a bandwidth from 100 to 1 kHz, saving 90% of the passives area and 25% of the FE power. Together with on-chip low dropout regulators (LDOs) and reference buffers, the prototype fabricated in 0.18- $\mu \text{m}$ CMOS technology has an active area of 0.72 mm2 and consumes a 12.3- $\mu \text{W}$ dc power. The APW (ExG) FE measures an input-referred noise of 5.84 (1.22) $\mu \text{V}_{\text {rms}}$ with a total-harmonic distortion of −80 (−81.8) dB.