This paper presents an ultrasound rangefinder system able to find relative distances among energy-constrained sensor nodes. The nodes build a swarm that is operated in collision and multipath rich environments. A new distance measurement technique combining Wake-up and Frequency Modulated Continuous Wave (FMCW) is proposed to enable the ranging while neglecting the echoes from passive reflectors in the environment. The building blocks of the sensor nodes comprise a transmitter, a wake-up receiver, and a ranging receiver, all implemented in a 65 nm CMOS technology. The transmitter includes two switched-capacitor converters and an output multiplexer to generate a four-level driving signal and broadcast either a wake-up sequence or a digitally synthesized ultrasound Chirp. The transmitter dissipates $0.43~\mu \text{J}$ and ${0.82~\mu \text {J}}$ to broadcast the wake-up signal and the Chirp, respectively. A mixer first architecture is exploited in the wake-up receiver to reduce the always-on power consumption of the nodes. The ranging receiver uses a heterodyne architecture suited for the FMCW. The power consumption of the wake-up receiver and ranging receiver is 23.6 nW and $0.56~\mu \text{W}$ , respectively. The proposed rangefinder is experimentally characterized up to a 1 m distance in air and dissipates $1.25~\mu \text {J}$ per measurement, achieving a resolution of 18.7 mm at 0.55 m.

中文翻译：

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1.25μJ的测量纳米超声测距仪系统采用65 nm CMOS，可用于大量传感器节点的勘探

本文提出了一种超声波测距仪系统，该系统能够找到能量受限的传感器节点之间的相对距离。节点构建了一个在冲突和多路径丰富的环境中运行的群体。提出了一种结合了唤醒和调频连续波（FMCW）的新距离测量技术，以实现测距，而忽略了环境中无源反射器的回波。传感器节点的组成部分包括一个发射器，一个唤醒接收器和一个测距接收器，所有这些均以65 nm CMOS技术实现。该发射器包括两个开关电容器转换器和一个输出多路复用器，以生成四电平驱动信号并广播唤醒序列或数字合成超声线性调频脉冲。发射器耗散 $ 0.43〜\ mu \ text {J} $ 和 $ {0.82〜\ mu \ text {J}} $ 分别播放唤醒信号和线性调频。在唤醒接收器中采用了混合器优先架构，以减少节点的始终在线功耗。测距接收机使用适用于FMCW的外差架构。唤醒接收器和测距接收器的功耗为23.6 nW， $ 0.56〜\ mu \ text {W} $ ， 分别。拟议中的测距仪在空气中的实验距离高达1 m，并会消散 $ 1.25〜\ mu \ text {J} $ 每次测量时，在0.55 m处实现18.7 mm的分辨率。