A 36 μW 1.1 mm² Reconfigurable Analog Front-End for Cardiovascular and Respiratory Signals Recording

Abstract

This paper presents a 1.2 V 36 μW reconfigurable analog front-end (R-AFE) as a general-purpose low-cost IC for multiple-mode biomedical signals acquisition. The R-AFE efficiently reuses a reconfigurable preamplifier, a current generator (CG), and a mixed signal processing unit, having an area of 1.1 mm2 per R-AFE while supporting five acquisition modes to record different forms of cardiovascular and respiratory signals. The R-AFE can interface with voltage-, current-, impedance-, and light-sensors and hence can measure electrocardiography (ECG), bio-impedance (BioZ), photoplethysmogram (PPG), galvanic skin response (GSR), and general-purpose analog signals. Thanks to the chopper preamplifier and the low-noise CG utilizing dynamic element matching, the R-AFE mitigates ${\text{1}}\text{/}f$ noise from both the preamplifier and the CG for improved measurement sensitivity. The IC achieves competitive performance compared to the state-of-the-art dedicated readout ICs of ECG, BioZ, GSR, and PPG, but with approximately 1.4×-5.3× smaller chip area per channel.

A 122 fps, 1 MHz Bandwidth Multi-Frequency Wearable EIT Belt Featuring Novel Active Electrode Architecture for Neonatal Thorax Vital Sign Monitoring

“…performance voltage acquisition front-ends for bioimpedance measurements have been reported [23], [24] but mainly for onechannel recording. Read-out chains for EIT that use current feedback IA for wideband, high CMRR have been also reported [25], [26].…”

A Power-Efficient Current Generator with Common Mode Signal Autozero Feedback for Bioimpedance Measurement Applications

“…The H-bridge based current generator is often implemented using two independent carefully matched PMOS and NMOS current mirrors to source and sink the current across the load as shown in Fig. 2(a) with no common mode feedback; this approach suffers from ∆ current mismatch due to process variations [10]. Some electrical bioimpedance systems use micro-electrodes which have high contact impedance (up to a tens of kΩ); whereas the tissue impedance is only few hundred Ohms and decreases to a few mΩ at high frequency.…”

“…The SPWM generator is fully digital where the LUT only contains 32 bits. On the other hand, SPWM provides significantly better SFDR than the square wave, which is also commonly used in EIS systems [10], [13].…”

Simultaneous Voltage and Current Measurement Instrumentation Amplifier for ECG and PPG Monitoring

“…A reconfigurable IA based on a current-balanced IA structure was published and showed various applications as shown in Figure 1b [8]. A reconfigurable IA based on a three OP amp IA structure was also published in [9]. In wearable and mobile environments, health monitoring devices use batteries.…”