A 60 $\mu$W 60 nV/$\surd$Hz Readout Front-End for Portable Biopotential Acquisition Systems

Abstract

There is a growing demand for low-power, small-size and ambulatory biopotential acquisition systems. A crucial and important block of this acquisition system is the analog readout front-end. We have implemented a low-power and low-noise readout front-end with configurable characteristics for Electroencephalogram (EEG), Electrocardiogram (ECG), and Electromyogram (EMG) signals. Key to its performance is the new AC-coupled chopped instrumentation amplifier (ACCIA), which uses a low power current feedback instrumentation amplifier (IA). Thus, while chopping filters the 1/f noise of CMOS transistors and increases the CMRR, AC coupling is capable of rejecting differential electrode offset (DEO) up to 50 mV from conventional Ag/AgCl electrodes. The ACCIA achieves 120 dB CMRR and 57 nV/ Hz input-referred voltage noise density, while consuming 11.1 A from a 3 V supply. The chopping spike filter (CSF) stage filters the chopping spikes generated by the input chopper of ACCIA and the digitally controllable variable gain stage is used to set the gain and the bandwidth of the front-end. The front-end is implemented in a 0.5 m CMOS process. Total current consumption is 20 A from 3V.

A Noise Reconfigurable Current-Reuse Resistive Feedback Amplifier with Signal Dependent Power Consumption for Fetal ECG Monitoring

“…There are two noise settings of the proposed amplifier: 0.4µVrms, (6.3µW power) and 2.6µVrms, (0.9µW power). The proposed topology achieves better power efficiency (NEF) than the resistive feedback topology in [5] thanks to the current reuse, the optimization of the input resistance for minimum power consumption, and the signal dependent current biasing. Even compared to capacitive feedback amplifiers without current reuse technique [7][8], the NEF of this amplifier is better.…”

“…Resistive feedback amplifiers offer high Zin and high CMRR, but suffer from relatively high NEF, mainly because the feedback resistors contribute to the total noise [5]. In this paper, a noise-reconfigurable current-reuse resistive feedback amplifier that achieves high power efficiency together with high input impedance is proposed and optimized in a standard 0.18µm CMOS technology.…”

A dual-core system solution for wearable health monitors

“…The system set-up for this experiment is depicted in Figure 3 where the ECG Front-end (FE) chip [6] amplifies and filters the ECG signals that are sampled by the ADC in the MSP430. During the simulation using WSim, only the dynamic behaviour of the ADC and the MSP430 are included and the ECG FE is taken as a constant in the total power figure.…”

Improving phase congruency for EEG data reduction

“…It also determines the size and duration of the battery. Power consumption could be reduced by either fully customizing the design of all the electronic blocks that form the EEG system [5] and/or coming up with strategies to reduce the amount of data that needs to be transmitted. This paper presents a data selection algorithm to identify candidate epileptic interictal activity and reject normal back- ground brain activity.…”