Monolithic component with an electrically variable capacitance

摘要

Components which have an electrically variable capacitance are virtually unknown: capacitance diodes having the disadvantages of small achievable capacitances and the limitation to small useful signals as well as multilayer ceramic capacitors having an additional electrode for altering the capacitance as a function of the field strength. The existing conductive (galvanic) coupling of useful signal and control signal is disadvantageous in this case. The novel component does not exhibit these disadvantages. The layered structure means that in a monolithic component two conventional components can be combined to form one: a capacitor and a resistor. If a power loss is produced in the resistor, the temperature of the component increases. This effects a change in the capacitance of the capacitor because of a change in the relative dielectric constant of the layer material. Separate pairs of connections make it possible to operate the component as an electrical four-terminal network. Distortion of the capacitor useful signal occurs only at high useful signal power. The preferred material is ferroelectric ceramic. The component can be used, for example, in electrically tunable resonant circuits, in controllable RC or LC elements or capacitive voltage dividers.