A high FoM lithium niobate resonant transformer for passive voltage amplification

This paper reports a lithium niobate (LiNbO3) resonant transformer with an extracted passive open-circuit voltage gain of 38. The result has been attained thanks to a high figure of merit (FoM=k
t
²
· Q) of 136 that results from a high electromechanical coupling (k
t
²
) of 28% and a high Q of 480. To our knowledge, this is the highest FoM that has been demonstrated for a two-port MEMS resonator. The fabricated transformer also features a factional bandwidth of 0.21%, thus providing a large operation temperature range (±18 K) over which a high gain can be maintained. This work has shown promising results for wake-up radio applications, where transformers can be exploited for detection of faint signals with very low or zero power consumption.