Matsushita Electric Industrial Co., Ltd.

Tomohiro Shika

Makoto Taromaru

A frequency modulator includes a reference frequency oscillator, a voltage controlled oscillator provided with a control input terminal and a modulation input terminal, a frequency divider for dividing an output of the voltage controlled oscillator, a phase comparator for generating an output signal corresponding to a phase difference between an output of the reference frequency oscillator and an output of the divider, a first filter having an input terminal and an output terminal, the input terminal thereof being connected to an output terminal of the phase comparator, while the output terminal thereof being connected to the control input terminal of the voltage controlled oscillator, and a second filter having an input terminal and an output terminal, the input terminal being inputted a modulating signal and the output terminal being connected to the modulation input terminal of the voltage controlled oscillator. The second filter has a lower amplitude characteristics in a low frequency range within a modulation frequency band than that in a high frequency range within the same.

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Kasuga, Japan

Tomohiro Shika