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

Journal article (2019)

Authors

H. Jiang Electronic Instrumentation - EEMCS
S. Nihtianova Electronic Instrumentation - EEMCS
K.A.A. Makinwa Microelectronics
Research Group
Electronic Instrumentation (EEMCS) (TU Delft)
Copyright: © 2019 H. Jiang, S. Nihtianova, K.A.A. Makinwa
DOI: https://doi.org/10.1109/JSSC.2018.2885556
Energy efficient Temperature compensation Beyond the rails Bridge offset compensation Bridge sensor Capacitively coupled (CC) chopper CC instrumentation amplifier (CCIA) Continuous-time delta-sigma modulator (CTΔ Σ M) Readout IC (ROIC)
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Published Date

2019

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Department

Microelectronics

Research Group

Electronic Instrumentation

Abstract

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
to block dc common-mode voltages, the bridge’s bias voltage may exceed the ROIC’s supply voltage, allowing these voltages to be independently optimized. Since bridge output is typically much smaller than bridge offset, a digital to analog converter (DAC) is used to compensate this offset before amplification and
thus increase the CCIA’s useful dynamic range. Bridge loading is reduced by using a dual-path positive feedback scheme to boost the CCIA’s input impedance. Furthermore, the CCIA’s output is gated to avoid digitizing its output spikes, which would otherwise limit the ROIC’s linearity and stability. The ROIC achieves an input-referred noise density of 3.7 nV/Hz, a noise efficiency factor (NEF) of 5, and a power efficiency factor (PEF) of 44, which both represent the state of the art. A pressure sensing system, built with the ROIC and a differential pressure sensor (AC4010), achieves 10.1-mPa (1) resolution in a 0.5-ms conversion time. The ROIC dissipates about 30% of the system’s power dissipation and contributes about 6% of its noise power. To reduce the sensor’s offset drift, a temperature compensation scheme based on an external reference resistor is used. After a two-point calibration, this scheme reduces bridge offset drift by 80× over a 50 °C range.