A ceramic capacitor for AC applications

A description is given of a multilayer ceramic capacitor developed for AC voltage operation by using a dielectric characterized by very low loss, even at large signal amplitudes. The result is a new class of ceramic capacitors useful in many medium power AC application such as line isolation and bypass to ground, small motor controls, etc. The dF of these ceramic capacitors compares favorably with that of small aluminium electrolyte capacitors. Comparable films are much larger, and the ceramic devices can be rated for much higher ambient temperature operation. Novel approaches to large-signal capacitor measurement, under conditions closely approximating use conditions, are presented for a range of low frequencies up to at least 10 kHz. It is demonstrated that at high frequencies, high resonant frequency and low series resistance are good figures of merit for capacitors