An Instinctually Adaptive Lamb-Wave Filter Using Nonlinear Hafnia-Zirconia Ferroelectric Transducer

Abstract

Reported is the first integrated instinctually adaptive acoustic filter with frequency-selective power-limiting characteristic. The passive filter is created from electrical coupling of hafnia-zirconia (Hf0.5Zr0.5O2) Lamb-wave resonators with configurable transduction between linear and quadratic piezoelectricity. Linear resonators are cascaded to create a bandpass response over fcenter ± 0.5∆f−3dB. Nonlinear resonators with frequencies spanning over the second order super-harmonic of the filter passband (i.e., 2fcenter ± 0.5∆f−3dB) are placed in shunt to serve as frequency-selective power-limiters (FSL) for instinctual, in-band interference cancellation through electromechanical scattering. Quadratic and linear piezoelectricity are achieved through voltage-dependent poling of Hf0.5Zr0.5O2 between ferroelastic and ferroelectric regimes. Nonlinear FSL and instinctually adaptive filter prototypes are demonstrated in 50nm-thick, atomic-layered Hf0.5Zr0.5O2. The FSL concept is demonstrated at 126 MHz based on a Lamb-wave resonance mode at 256 MHz, providing frequency selective limiting of over 20dB for input powers exceeding ─10dBm. Further, an adaptive filter operating at 617 MHz provides more than 10dB of in-band isolation at three equally spaced frequencies, for 14dBm input power. The presented instinctually adaptive filter concept is poised to replace computationally demanding cognitive interference management approaches and substantially reduce the latency, size, and power consumption of jamming immune RF front ends.