Measurement of the Characteristics of High-Q Ceramic Capacitors

The quality factor, equivalent series resistance, and the · frequency of self-resonance are parts of the specifications of high-Q ceramic capacitors. These quantities are obtained from measurements on transmission lines with the capacitor in series or shunt. Part A: Resonant structures designed to extend the Electronics Industries Association (EIA) standard RS-483 downwards below 10 MHz and upwards above 3 GHz are discussed. For the low-frequency lines, a rule for extrapolating Q values outside the range of data is proposed. The rule is based on the frequency-dependence of the input/output coupling. The high-frequency line incorporates a method of tuning which eliminates the need for interpolation or extrapolation. It is particularly suited to measuring small parallel-plate capacitors which can be mounted on a flat shorting plate. Part B: It is shown that the first self-resonance, when viewed in terms of a series R, L, C equivalent circuit, is a poorly defined quantity. It is not always observable; it may not exist; and it may be of minor importance to design applications, it is proposed that the resonance specification of capacitors should be the first parallel resonance, defined as the first maximum in dissipation loss.