Losses in Ferroelectric Dielectric Ceramic Capacitors due to Electromechanical Resonances

The effect of electromechanical resonances (EMR) caused by the inverse piezoelectric effect on the losses in ferroelectric dielectric ceramic capacitors (FDCC) is analyzed. The EMR are visible in the equivalent series resistance (ESR) and depend on the DC voltage bias. The ESR of FDCCs is measured with a vector network analyzer (VNA) and additional DC bias between 10 kHz and 50 MHz in order to locate the EMR frequencies. Furthermore the losses in a buck converter’s output capacitor are measured calorimetrically when operating the converter at and beside an EMR frequency, respectively. When operating the converter at an EMR frequency the losses increase significantly.