Dual-electrode pMUT with Switch Mode Operation to Enhance Receive Sensitivity

Piezoelectric Micromachined Ultrasonic Transducers (pMUTs) with circular geometries traditionally employ an electrode radius of 70% of the elastic membrane radius to maximize Transmit (Tx) sensitivity, particularly for Time of Flight (TOF) applications. However, this configuration compromises Receive (Rx) sensitivity due to decreased charge generation per unit electrode area as the electrode ratio increases. This study proposes and evaluates a novel dual-electrode pMUT design with switch mode operation to enhance overall performance. In our approach, both inner and outer electrodes, collectively covering 70% of the membrane area, are utilized for Tx mode, while only the inner electrode is connected to the read-out circuit during Rx mode. Finite element simulations and experimental validations demonstrate that this design significantly improves Rx sensitivity by 33% compared to conventional single electrode configuration, while maintaining optimal Tx performance.