Wake-up receivers have been proposed to provide continuous sensing in a wide variety of Internet of Things applications. To achieve impedance transformation and passive amplification between the antenna and rectifier node, current wake-up receivers employ large magnetic transformers that exhibit both low Q and inductance per unit area in planar CMOS technology. The adoption of piezoelectric MEMS resonators to replace magnetic transformers offers an area-efficient, high-Q, monolithic solution that allows large voltage amplification for ultra-low-power applications. AlN Contour Mode Resonators (CMRs) are an emerging class of piezoelectric MEMS that offers frequency reconfiguration via lithography.