An Energy-Efficient 3.7-nV/√ Hz Bridge Readout IC With a Stable Bridge Offset Compensation Scheme

This paper describes an energy-efficient bridge readout IC (ROIC), which consists of a capacitively coupled instrumentation amplifier (CCIA) that drives a continuous-time delta–sigma modulator (CTM). By exploiting the CCIA’s ability<br/>to block dc common-mode voltages, the bridge’s bias voltage may exceed the ROIC’s supply voltage, allowing...

A 0.5 μA/Channel front-end for implantable and external ambulatory ECG recorders

There is an increasing demand for low power, low voltage, and small size analog readout bio-potential systems. This paper presents an analog front-end for measuring the intra-cardiac signals in implantable and also external ambulatory ECG cardiac recording applications. The analog front-end benefits from voltage to frequency conversion...

Energy-Efficient Bridge-to-Digital Converters

This paper presents an overview of energy-efficient analog-to-digital converters (ADCs) specifically intended for the readout of Wheatstone bridge sensors. Apart from achieving good energy-efficiency, such bridge-to-digital converters (BDCs) must achieve low input-referred offset, drift and noise; high gain accuracy, stability and linearity;...

A 0.6V 3.8μW ECG/bio-impedance monitoring IC for disposable health patch in 40nm CMOS

Simultaneous measurement of Electrocardiogram (ECG) and bio-impedance (BioZ) via disposable health patches is desired for patients suffering from chronic cardiovascular and respiratory diseases. However, a sensing IC must consume ultra-low power under a sub-volt supply to comply with miniaturized and disposable batteries. This work presents...

A 4.5 nV/√Hz Capacitively Coupled Continuous-Time Sigma-Delta Modulator with an Energy-Efficient Chopping Scheme

When chopping is applied to a continuous-time sigmadelta modulator (CTΣΔM), quantization noise fold-back often occurs, leading to increased in-band noise. This can be prevented by employing a return-to-zero (RZ) digital-to-analog converter (RZ DAC) in the modulator's feedback path and arranging the chopping transitions to coincide with its RZ...

Active Electrodes for Wearable EEG Acquisition: Review and Design Methodology

Active electrodes (AEs), i.e., electrodes with built-in readout circuitry, are increasingly being implemented in wearable healthcare and lifestyle applications due to AEs' robustness to environmental interference. An AE locally amplifies and buffers μV-level EEG signals before driving any cabling. The low output impedance of an AE mitigates...

A 20-bit ±40-mV Range Read-Out IC With 50-nV Offset and 0.04% Gain Error for Bridge Transducers

This paper presents a 20-b read-out IC with ±40-mV full-scale range that is intended for use with bridge transducers. It consists of a current-feedback instrumentation amplifier (CFIA) followed by a switched-capacitor incremental ΔΣ ADC. The CFIA's offset and 1/ <i>f</i> noise are mitigated by chopping, while its gain accuracy and gain drift are...

Fully Integrated Analog Front-end for a 2-electrode ECG device

Cardiovascular diseases are leading cause of deaths worldwide. With increasing graying population and limited health infrastructure there is a need for portable and implantable ECG devices to diagnose these diseases early on. In general an ECG device requires three or more electrodes, which need to be applied to the body via a gel, to obtain a...

A Current-Feedback Instrumentation Amplifier With 5 µV Offset for Bidirectional High-Side Current-Sensing