Power-Efficiency Evolution of Capacitive Sensor Interfaces

Recent years have witnessed an improvement in the energy efficiency of capacitive sensor interfaces by more than three orders of magnitude. This article reviews the architectural and circuit innovations that have contributed to this progress. The fundamental limit on the energy consumption of capacitive sensor interfaces is discussed, as well...

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 117DB in-Band CMRR 98.5DB SNR Capacitance-to-Digital Converter for Sub-NM Displacement Sensing with an Electrically Floating Target

This paper describes a high-performance Capacitance-to-Digital Converter (CDC) for sub-nm displacement sensing with an electrically floating target. Intended to be integrated into a displacement sensor probe, the CDC consumes only 560μW. It achieves 98.5dB SNR in a 1ms conversion time, which is 34 times more energy-efficient than the prior...

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...

A Power-Efficient Readout for Wheatstone-Bridge Sensors With COTS Components

This paper presents a direct digital converter for Wheatstone bridge sensors, which is realized with commercial off-the-shelf components. The power efficiency of the readout is enhanced by embedding the bridge sensor in a second-order continuous-time sigma-delta modulator (CTDeltaSigmaM). By directly digitizing the output signal of a Wheatstone...