A frequency synthesizer comprises: a single-tone signal generator which outputs signals of a single frequency; a frequency multiplier which generates one or more intermediate signals having different frequencies based on frequencies of input signals and outputs the same as output signals; a frequency selector; a mixer; and a frequency synthesizer control circuit which includes a frequency synthesizer control terminal, wherein an output of the single-tone signal generator is set as an input of the frequency multiplier, one or more outputs of the frequency multiplier are set as one or more inputs of the frequency selector, an output of the frequency selector and one output of the outputs of the frequency multiplier are set as first and second inputs of the mixer, and an output of the mixer is set as an output of the frequency synthesizer.