An Ultrasonic Driver Array in Metal-Oxide Thin-Film Technology Using a Hybrid TFT-Si DLL Locking Architecture

Abstract

This article presents a 24-V high voltage (HV) ultrasonic driver for haptic feedback, designed to drive piezoelectric micromachined ultrasonic transducers (PMUTs) using a unipolar 0.8 mu m indium-galium-zinc-oxide (IGZO) thin-film transistor technology fabricated on a polymer substrate. A new hybrid silicon/IGZO DLL architecture is proposed to overcome the IGZO technology shortcomings by leveraging the accuracy and speed capabilities of silicon technologies. The ultrasonic driver is able to drive a transducer capacitance up to 36 pF with a 3.54 bit phase resolution and a frequency of 250 kHz occupying a pitch-matched area per pixel of 800 x 800 mu m. This work shows the first fully integrated high-voltage ultrasonic driver realized in thin-film transistor technology. As the proposed hybrid architecture enables large active driver arrays at a fraction of the cost of silicon solutions, a new range of applications can be envisioned, such as large ultrasonic haptic feedback matrices.