To obtain a clock frequency generator that can output a transmission signal waveform much, including a power component with a transmission clock frequency with respect to an input of an optional data signal waveform.

This clock frequency generator is provided with NPN transistors(TRs) 15, 16, whose collectors receive a high level power supply voltage and whose bases receive a data signal or an inverted data signal to configure a differential pair, a current source 18 whose one terminal is connected to emitters of the NPN TRa 15, 16 and whose other terminal receives a low level power supply voltage, and an offset voltage adjustment circuit 20 that absorbs an offset voltage caused by dispersion in characteristics of the NPN TRs by giving a voltage to offset control terminals respectively assigned to the data signal and the inverted data signal. A desired output signal can be obtained from the one terminal of the current source 18.