To expand a frequency variable range by inserting the first variable capacitance diode to one of the capacitors of an LC circuit part, serially inserting the second variable capacitance diode to a crystal oscillator, controlling external voltage to be applied to the first and second variable capacitance capacitors and simultaneously varying the capacitance of the variable capacitance capacitors.

The resonance frequency of an LC circuit part is decided by the composed capacity of a coil L5, a capacitor C7, a capacitor C6 and a variable capacitance diode D2. In addition, a filtering frequency is decided by a crystal oscillator Y4 and a variable capacitance diode D1 to set this filtering frequency component to be the output of a call originating circuit. In the case of increasing the value of controlled voltage Vcont in constitution like this, the capacitance values of the diodes D1 and D2 are increased to operate to respectively lower the call originating frequency of the LC circuit part and a filtering frequency.