Use of Supporting Post Width to Increase the CMUT’s Resonant Frequency

Wang, Jiujiang; Pun, Sio Hang; Yu, Yuanyu; Liu, Yihe; Cheng, Ching-Hsiang; Lei, Kin Fong; Zhang, Shuang; Mak, Peng Un; Vai, Mang I

doi:10.1109/access.2022.3178990

Cited by 4 publications

(1 citation statement)

References 32 publications

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“…These works employed tri-level or multi-level pulsing for enhanced energy efficiency. The aforementioned works paid little attention on an optimum center frequency, even though a deviation of center frequency of MEMS based transducer is not negligible [17][18][19]. In addition, a center frequency of transducer along with quality factor can vary depending on an input power, an ambient temperature, and an acoustic loading condition of medium [6][7][8][9][10]20].…”

Section: Introductionmentioning

confidence: 99%

Center Frequency Tracking Scheme to Optimize Pulse-Echo Response of Ultrasonic A-mode Scanner Circuit System

Lee

2023

IEEE Access

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This paper proposes a center frequency tracking scheme to optimize a pulse-echo response of ultrasonic A-mode scanner. A pulse-echo response of A-mode scanner represents an overall energy conversion characteristic from an actuation to an acquisition. A center frequency for optimized pulse-echo response can be varied depending on an actuation voltage, an acoustic medium, etc. Most of previous frequency tracking methods have focused on high-power continuous actuation applications, and have relied on a monitoring of phase difference between actuating voltage and current with auxiliary sensors. This work focuses on a monitoring of a peak envelope of echo without additional sensors. We employ a momentum based gradient ascent algorithm along with a finite state machine to track an optimum center frequency so that a peak envelope of echo becomes the maximum value. The proposed frequency tracking scheme was implemented on a field programmable gate array for real-time operation. We performed repetitive measurements to verify consistent frequency tracking performances for different acoustic mediums. The A-mode scanner adaptively tracked corresponding center frequencies for each of mediums within an average error of 61.7 kHz. When the A-mode scanner was in a steady state, an increment of signal-to-noise ratio (SNR) of echo was 7.4 dB, and an axial resolution was improved by 32.5 %.INDEX TERMS Center frequency tracking, A-mode ultrasound, gradient-ascent algorithm, momentum optimization, finite state machine, field programmable gate array, A-mode scanner circuit system.

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