X-Cut Lithium Niobate Series-Parallel Resonator Configuration Boosts Passive Voltage Amplification for Wake-Up Receivers to 46 V/V

This work reports on the use of X-cut Lithium Niobate (LN) microelectromechanical resonators in a series-parallel configuration (L-network) to boost passive voltage amplification in asynchronous Wake-Up Radio Receivers (WuRx) to 46 V/V – the highest passive voltage gain ever attained for WuRx with large capacitive input impedance ( $C_{\text{load}}$ ). We harness the quality factor ( $Q_{\mathrm{s}} > 4000$ at 50 MHz) and electromechanical coupling ( ${k_{\mathrm{t}}}^{2} > 30\%$ ) of X-cut LN resonators and configure them in a series-parallel network to provide passive voltage amplification when driving a capacitive load (e.g. the input impedance of an envelope detector). The use of this L-network is disruptive over the conventional use of a single series resonator and provides more than 30% gain improvement. The proposed technique requires two identical resonators and is robust against frequency variations. Finally, it requires the use of smaller resonators for a given capacitive load, making it further immune to gain variations experienced when using large parallel arrays of resonators.