A System in Package Based on a Piezoelectric Micromachined Ultrasonic Transducer Matrix for Ranging Applications.

Area of Science:

• Microelectromechanical Systems (MEMS)
• Ultrasonic Transducer Technology
• Integrated Circuit Design

Background:

• Ultrasonic ranging systems are crucial for applications requiring precise distance measurement.
• Developing compact and efficient ultrasonic systems necessitates advancements in transducer and interface circuit integration.
• Existing systems often face challenges in miniaturization and performance optimization.

Purpose of the Study:

• To propose and validate a system-in-package (SiP) for ultrasonic ranging.
• To integrate a 4x8 matrix of piezoelectric micromachined ultrasonic transducers (PMUTs) with a custom interface integrated circuit (IC).
• To optimize the performance of the ultrasonic ranging system at a working frequency of 1.5 MHz.

Main Methods:

• Fabrication of the PMUT matrix using the PiezoMUMPS process.
• Implementation of the interface IC using AMS 0.35 µm technology.
• Development of an equivalent circuit model for accurate PMUT load approximation on the IC.
• Design of a control circuit including a high-voltage pulser and a transimpedance amplifier.

Main Results:

• Successful fabrication and integration of the PMUT array and interface IC.
• Validation of simulation results against measurement data for the PMUTs.
• Demonstration of effective signal transmission and echo amplification at 1.5 MHz.
• Characterization of the PMUT load on the IC using the derived equivalent circuit.

Conclusions:

• The proposed SiP effectively integrates PMUTs and an IC for ultrasonic ranging.
• The developed system achieves reliable performance at 1.5 MHz.
• The equivalent circuit model aids in optimizing the interface IC design for PMUTs.