BAW Transformer for Rectenna Using 12-Layer Polarization Inverted Structure

Passive voltage transformers are attractive for the application in a rectenna which allows the energy harvesting from weak ambient electromagnetic waves. We proposed a piezoelectric transformer using polarization inverted 12-layer ScAlN. By increasing the number of polarization inverted layers, both high voltage gain and relatively broadband characteristics were achieved. The voltage gain of 6 and active bandwidth of 30 MHz were experimentally obtained in 600 MHz range. The experimental result shows good agreement with theoretical electromechanical transmission line model.