Voltage controlled oscillating circuit

摘要

A voltage controlled oscillating circuit operable to output a variable frequency, includes a variable capacitance element with the variable frequency varying with a variation in capacitance of the variable capacitance element. The variable capacitance element is provided by a bipolar transistor. The capacitance of the variable capacitance element is achieved by combining the capacitance by the PN junction between the emitter layer and the base layer and capacitance formed by the PN junction between the base layer and the collector layer in a bipolar transistor, and is controlled by a voltage applied between the emitter layer and the collector layer of the bipolar transistor.