AT-Cut Quartz Piezoelectric Transformers for Passive Voltage Gain in an RF Front-End

The purpose of this work is to assess the performance of an AT-cut quartz device as a two-port resonant transformer for near-zero power-consuming wake-up receiver applications. The device consists of two, coupled thickness-shear mode trapped-energy ~50 MHz resonators on a single quartz substrate. Passive voltage gain up to 84 V/V (referenced to 50Ω) is observed when the device is driven by a low-power signal (≤ -30 dBm) at resonance. This transformer offers high voltage gain suitable for use in the front-end of a near-zero-power wake-up receiver. Additionally, this work shows that connecting two coupled-resonator quartz devices in a parallel-input, series-output (PISOT) configuration provides improvements in voltage gain. A 17% increase in gain is demonstrated for PISOT over that of a single coupled resonant transformer for various load impedances. This work is the first use of quartz piezoelectric transformers (PTs) for passive voltage gain, and the highest open-circuit gain demonstrated in a two-port micromechanical PT.