Noise characteristics of piezoelectric-transformer DC-DC converter

A piezoelectric-transformer (PT) is expected for a low-electric-noise device because it transmits power by mechanical vibration. However, there has been no study about noise of the PT so far. In this paper, we propose a model which focuses on a parasitic impedance of the PT, and compare its simulated result with an observed common-mode noise in the PT DC-DC converter to confirm a mechanism of the common-mode noise occurrence. As a result, we found that the parasitic impedance between the input and output terminals of the PT provides the path for common-mode noise. Furthermore, we propose an improved version of the PT DC-DC converter to reduce the common-mode noise, that is based on this noise analysis. As a result, drastic noise reduction was achieved.