Chiu Yihsiang, Wang Chen, Gong Dan, Li Nan, Ma Shenglin, Jin Yufeng
School of Electronic and Computer Engineering Bldg. A, Peking University Shenzhen Graduate School, University Town, Xili, Nanshan, Shenzhen 518055, China.
Department of Mechanical & Electrical Engineering, School of Aeronautics and Astronautics, Xiamen University, Xiamen 361005, China.
Micromachines (Basel). 2021 Mar 8;12(3):284. doi: 10.3390/mi12030284.
This paper presents a high-accuracy complementary metal oxide semiconductor (CMOS) driven ultrasonic ranging system based on air coupled aluminum nitride (AlN) based piezoelectric micromachined ultrasonic transducers (PMUTs) using time of flight (TOF). The mode shape and the time-frequency characteristics of PMUTs are simulated and analyzed. Two pieces of PMUTs with a frequency of 97 kHz and 96 kHz are applied. One is used to transmit and the other is used to receive ultrasonic waves. The Time to Digital Converter circuit (TDC), correlating the clock frequency with sound velocity, is utilized for range finding via TOF calculated from the system clock cycle. An application specific integrated circuit (ASIC) chip is designed and fabricated on a 0.18 μm CMOS process to acquire data from the PMUT. Compared to state of the art, the developed ranging system features a wide range and high accuracy, which allows to measure the range of 50 cm with an average error of 0.63 mm. AlN based PMUT is a promising candidate for an integrated portable ranging system.
本文提出了一种基于飞行时间（TOF）的高精度互补金属氧化物半导体（CMOS）驱动的超声波测距系统，该系统采用基于空气耦合氮化铝（AlN）的压电微机械超声换能器（PMUT）。对PMUT的振型和时频特性进行了模拟和分析。应用了两片频率分别为97kHz和96kHz的PMUT。一片用于发射超声波，另一片用于接收超声波。时间数字转换电路（TDC）将时钟频率与声速相关联，用于通过根据系统时钟周期计算出的TOF进行测距。设计并在0.18μm CMOS工艺上制造了一个专用集成电路（ASIC）芯片，以从PMUT获取数据。与现有技术相比，所开发的测距系统具有测量范围广和精度高的特点，能够测量50cm的距离，平均误差为0.63mm。基于AlN的PMUT是集成便携式测距系统的一个有前途的候选者。
