Ferroelectric thin film acoustic devices with electrical multiband switching ability

Abstract

Design principles of a new class of microwave thin film bulk acoustic resonators with multiband resonance frequency switching ability are presented. The theory of the excitation of acoustic eigenmodes in multilayer ferroelectric structures is considered, and the principle of selectivity for resonator with an arbitrary number of ferroelectric layers is formulated. A so called “criterion function” is suggested that allows to determine the conditions for effective excitation at one selected resonance mode with suppression of other modes. The proposed theoretical approach is verifiedusing thepreexisting experimental data published elsewhere. Finally, the possible application of the two ferroelectric layers structures for switchable microwave overtone resonators, binary and quadrature phase-shift keying modulators are discussed. These devices could play a pivotal role in the miniaturization of microwave front-end antenna circuits.

Formation of Millimeter Waves with Electrically Tunable Orbital Angular Momentum

“…Possible use of thin/thick film high-resistive electrodes can decrease this value down to 5 dB. For example, indium tin oxide (ITO) is suitable because its surface resistance is up to 10 MOhm/square [25]. Resistive alloys such as silicides of chromium, nickel, iron, and binary and ternary systems on their base are perspective materials for transparent electrodes.…”

“…Arguably, the value of control voltage used in the presented prototype is relatively high and this could be considered to be an obstacle for its practical implementation. A way around this challenge is to use a multilayer ferroelectric structure with individual voltage control [26]. Additionally, to improve the device performance (i.e., insertion loss, responsivity (to control voltage), etc.…”

From Microwave Acoustic Filters to Millimeter-Wave Operation and New Applications

“…Switched-mode reconfigurable ferroelectric based acoustic resonators have also been recently introduced [106], [107], [108]. Switched mode acoustic resonators containing multiple layers of half wave ferroelectrics can operate at different frequency bands without compromising k 2 [108].…”

Design and numerical demonstration of a 2D millimeter-wave beam-scanning reflectarray based on liquid crystals and a static driving technique

“…For reconfigurable arrays, electronically tunable devices, such as phase shifters, resonators, and antennas, have been crucial in applications requiring beam forming and beam scanning [1][2][3]. Phase shifters, such as MEMS [4,5], PIN or varactor diode [6][7][8][9], ferroelectric [10][11][12] and liquid crystals (LCs) [13,14] have been used to construct the array elements. As the frequency increases to millimeter-wave band, MEMS or diode based arrays [15,16] are difficult to manufacture, and present high losses and parasitic effects because the package size and the wavelength are comparable, while ferroelectric films have significant losses above 40 GHz [17].…”