A micropower dry-electrode ECG preamplifier

Abstract

This paper describes the development of a very low-power preamplifier intended for use in pasteless-electrode recording of the human electrocardiogram. The expected input signal range is 100 microV-10 mV from a lead-II electrode configuration. The amplifier provides a gain of 43 dB in a 3-dB bandwidth of 0.05 Hz-2 kHz with a defined high input impedance of 75 M omega. It uses a driven common electrode to enhance rejection of common-mode interfering signals, including low-frequency motion artifact, achieving a common-mode rejection ratio (CMRR) of better than 80 dB over its entire bandwidth. The gain and phase characteristics meet the recommendations of the American Heart Association, ensuring low distortion of the output ECG signal and making it suitable for clinical monitoring. The amplifier has a power consumption of 30 microW operating from a 3.3-V battery and is intended for use in small, lightweight, portable electrocardiographic equipment and heart-rate monitoring instrumentation.

Low-Frequency Response and the Skin-Electrode Interface in Dry-Electrode Electrocardiography

“…The following question however was immediately raised: how should the recording amplifier be adapted to the high source impedance commonly associated with dry electrodes? Optimised designs of the amplifier front-end have usually involved measuring the impedance of the skin-electrode interface (Burke & Gleeson, 2000;Chang et al, 2010;Ko et al, 1970;Mühlsteff & Such, 2004;Valverde et al, 2004). Some solutions have then inserted resistors in series with unbalanced electrodes to match the effective impedance seen at each input of the recording amplifier (Lee et al, 2006).…”

An Improved Very Low-Power Electrode Contact Impedance Monitor

“…This is a three-stage instrumentation ECG amplifier adapted from an earlier design by Burke & Gleeson [5] and later improved by Assambo & Burke [6]. The 46dB of differential gain is split primarily between the first stage with 14.4dB and the second stage with 25.6dB while the third stage provides 6dB of the gain with differential-tosingle-ended conversion.…”

A Survey on Instrumentation Amplifiers used for Biomedical application

“…In Figure 8, the conventional Instrume In Figure 8, the conventional Instrumentation amplifier is designed with the op-amp consisting of folded cascade amplifier with choppers to reduce noise and CMFB(Common Mode Feedback ) [20].To reduce the flicker noise and to increase the range of the input common mode voltage, PMOS transistors(Mp1-Mp3) are used. With the transistors (Mp6-Mp9) PMOS and (Mn3-Mn6) NMOS, the residual offset is eliminated, hence low power is acquired [21].…”