An electronic circuit that produces an output frequency which is an integral multiple of the input frequency. There are three basic types of frequency multipliers. The first type is a nonlinear amplifier that generates harmonics in its output current and a tuned load that resonates at one of these harmonics. The second type uses the nonlinear capacitance of a junction (semiconductor) diode to couple energy from the input circuit, which is tuned to the fundamental frequency, to the output circuit, which is tuned to the desired harmonic. The third type of multiplier uses a frequency divider in a locked-oscillator circuit.