UC Davis

A monolithic piezoelectric MEMS-CMOS resonant transformer that can be used in ultra-low-power high-efficiency RF sensing applications is presented for the first time. The MEMS-CMOS resonant transformer is based on a 59 MHz 2-port Aluminum Nitride (AlN) Contour Mode Resonator (CMR) bonded to a 0.18 μm NMOS-based rectifier for voltage boosting and RF-to-DC conversion. The integrated device is fabricated in a foundry-based process by conductive eutectic wafer bonding. To amplify the voltage, the AlN CMR is designed to attain a large quality factor (Q=1150) and a relatively low dielectric capacitance (C0=1.51 pF) in relation to the number of rectifier stages (n=20). As a result, a ten-fold voltage gain MEMS-CMOS resonant transformer is demonstrated in this work.