THE main advantages of piezoelectric transformers (PTs) are potential low cost, small size, low profile, good insulation capability, and the absense of windings, and hence, magnetic fields. In some specific applications, PTs are superior to electromagnetic transformers, making the PT a good design choice. Among these is the generation of a low power, high dc voltage (HV). Rosen type (see Fig. 1) PTs have a high gain ratio that, when combined with excellent insulation properties of the PT, make it a good candidate for the construction of compact HV converters—up to few kilovolts. Since the PT is a resonant element, its output to input voltage gain is strongly dependent on the operating frequency [1].