1-Port Piezoelectric Resonators With > 100 V/V Gain

This paper presents a 1-port thickness-shear (TS) mode quartz resonator with very high voltage gain, suitable for use in “near-zero-power” radios. These devices offer voltage gains >100× (referenced to 50 Ω) at ~50 MHz and >300× at ~75 MHz with ~60 fF load, which is the highest voltage gain directly measured to date in a piezoelectric micromechanical resonator. Six resonators with resonance fr≈ 50 MHz and identical electrode dimensions are characterized by S11measurements and by directly measuring the voltage gain using a high-impedance active probe. Quality factor (Q) up to 140,000 at ~50 MHz and electromechanical coupling (keff2) up to 0.445% are demonstrated. In several devices, voltage gain around or above 100 V/V is observed for load C ≈ 60 fF, and the gain changes as expected with decreasing load impedance. Additionally, a similar 1-port quartz resonator design at fs≈ 75 MHz is demonstrated to have voltage gain over 300 V/V (referenced to 50Ω) and Q around 335,000. These quartz resonators are fabricated in a mature, commercially available process, promoting widespread integration into radio-frequency (RF) wake-up receivers (WURs).