Frequency Multiplication In Circuits With Abrupt Junction Varactor Diodes

Frequency Multiplication in Circuits with Abrupt-junction Varactor Diodes

Circuits are analyzed, which utilize abrupt-junction varactor diodes, to generate harmonics of the frequency of the applied pump voltage. As original ideas, the varactor diode is represented by an equivalent circuit, in which the generation of the harmonics is ascribed to a nonlinear voltage source; and the Fourier coefficients of the solutions are represented as power series of the pump amplitude. For any order of harmonic generation, the nonlinear dependence of the Fourier coefficients on the pump amplitude is expressed by auxiliary functions. These functions form an infinite system of equations which has as parameters only the normalized pump voltage and the network functions of the linear circuit, which originates if the varactor diode is replaced by the series connection of a linear condenser and a resistance. Due to the pumping process, the d. c. charge of the varactor diode is reduced and the average capacitance of the diode increases. It is assumed that the associated detuning of the circuit is corrected by suitably increasing the bias voltage of the diode. All interesting quantities, such as input impedance, output power and efficiency can be expressed as a function of the pump amplitude with only one auxiliary function, which is characteristic for the given circuit. Frequency doubling and frequency tripling with idler are analyzed in detail. For frequency doubling, xthe results of maximum drive-level operation are presented and optimum design rules are established for four different requirements. (Author).

Technical Abstract Bulletin

An X-band Signal Source by Varactor Diode Frequency Multiplication