A 7.5‐μW 0.08‐mm² single‐ended SC delta‐sigma ADC for acoustic sensor applications

Abstract

This study presents an ultra-low-power, small-size, 1-bit, single-ended, and switched-capacitor (SC) deltasigma analog-to-digital converter (ADC) for wireless acoustic sensor nodes. This wireless sensor node has a delta-sigma ADC that converts the sensed signal to a digital signal for convenient data processing and emphasizes the features of small size and low-power consumption. The chip area of the delta-sigma ADC is dominated by the capacitor; therefore, a novel common-mode (CM) controlling technique with only transistors is proposed. This ADC achieves an extremely small size of 0.08 mm 2 in a 130-nm CMOS process. The conventional operational transconductance amplifiers (OTAs) are replaced by inverters in the weak inversion region to achieve high power efficiency. At 4-MHz sampling frequency and 0.7-V power supply voltage, the delta-sigma ADC achieves a 55.8-dB signal-to-noise-plus-distortion ratio (SNDR) and a 298-fJ/step figure-of-merit (FOM) in a signal bandwidth of 25 kHz, while consuming only 7.5 μW of power.

Design and experimental study of a piezoelectric energy harvester in automotive spokes

“…The energy harvesters described herein can be used for some low-consumption electronic devices. For example, the commercial acceleration sensor ADXL362 from Analog Devices, Inc. (ADI) consumes 3.6 μW at the sample rate of 100 Hz, a study of ADC chips for acoustic sensors can consume as little as 7.5 μW [35], a study on the wireless wake-up receiver can consume as little as 6.1 nW [36].…”

Application of class D power amplifiers in low power potentiostat circuits

“…In this work a low power potentiostat was presented. Sigma‐delta based signal processing techniques are usually an effective approach for efficient enhancement . In the presented work not only a sigma‐delta architecture was used in the circuit topology but the output stage was also modified to a switching amplifier which significantly enhances power usage.…”

Readout Circuits for Capacitive Sensors

“…The bandwidth of the Op Amp must be increased to drive at a high driving frequency, which leads to an increase in the power consumption of the Op Amp. Therefore, a structure that does not need to increase the bandwidth of the Op Amp is adopted to lower the power consumption of the delta-sigma ADC [ 55 ], or an inverter-based amplifier is used to lower the power consumption and maintain a high bandwidth [ 56 ].…”