With high power density and quality factor, piezoelectrics have emerged as a promising alternative to replace magnetics. However, piezoelectrics have mostly been explored in the context of dc-dc converter with off-the-shelf piezoelectrics. This paper presents a novel piezoelectric transformer (PT), which is suitable for power amplifier and can easily scale for different conversion ratios. The proposed PT is vertically stacked, with a quartz in the middle for mechanical coupling. Primary and secondary sides of the PT are mounted on two sides of the quartz which eases the scaling for the transformer ratio. A prototype PT is built and tested to verify the proposed structure, with conductive traces additively manufactured using silver paste for high conductivity and rapid prototyping. Finally, the equivalent circuit of PT is modeled and analyzed which agrees both with COMSOL simulation and experimental results. Our prototype has only 6mm×6mm area which has the potential of improving power density by eliminating air-core inductor which is conventionally used in high-frequency power amplifier.
