Optimization of MEMS Matching Network for the Sensitivity of GHz Low-Power Wake-Up Receivers

This work presents a detailed study on the design of microelectromechanical system (MEMS) matching networks (MN) for low-power wake-up receivers (WuRX) operating in GHz frequency bands. To enhance the WuRX sensitivity, a co-design theory between the MN and CMOS energy detector (ED) is proposed and derived quantitatively to give the optimal circuit topology and design under different scenarios of effective quality factor ( $Q_{eff}$ ), when the MEMS resonator is modeled as an effective inductive ( $L_{eff}$ ) matching element. To verify the proposed design theory as well as the high performance of MEMS MN (MMN), CMOS ED chips and various FBAR resonators of different sizes were fabricated and tested. Measurement results show that the demonstrated MMN achieves relative sensitivity gain ( $A_{sens}$ ) and voltage gain ( $G_{v}$ ) of 8.6 dB and 19.9 dB, respectively. The measured $A_{sens}$ is the highest among all reported MMNs with similar ED input capacitance operating at GHz frequencies.[2024-0090]