| 摘要 |
In the current-controlled oscillator performing an oscillation frequency control by using a differential amplifier circuit, resistors are inserted to each current path of a differential pair of the differential amplifier circuit, and thereby an inclination of output currents Ia, Ib of a differential pair is small in the linear line region. Further, by setting a reference voltage applied to a base of a transistor of one side of the differential pair lowly, the linear region is shifted to low voltage side, and thereby a saturation region of the low voltage side is not occurred. Moreover, when a comparison result of a phase of an output signal of the current-controlled oscillation circuit and a reference signal is converted to an oscillation frequency control voltage V<SUB>tune</SUB>, by limiting an upper limit voltage of the V<SUB>tune </SUB>by an output of a regulator in stead of a positive voltage power source V<SUB>cc </SUB>of common circuit, the V<SUB>tune </SUB>does not move to a saturation region upper than the linear region. According to the current-controlled oscillator, it is possible to prevent deterioration of a phase noise characteristic or deadlock caused by an inclination or a width of the linear region of the output characteristic of the differential amplifier circuit.
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