| 摘要 |
PROBLEM TO BE SOLVED: To provide an oscillator in which circuit characteristics are balanced without being affected by noise from a signal line and a power line, and a PLL circuit utilizing the oscillator, or communication equipment utilizing the oscillator or the PLL circuit. SOLUTION: The oscillator provided with a resonance circuit has a first serial connection circuit 88 having coils 1 and 2 and a power supply terminal 17, a second serial connection circuit 89 having capacitors 3 and 5 and a varactor 4 having directivity in its characteristics, and a third serial connection circuit 90 having capacitors 10 and 12 and a varactor 11 having directivity in its characteristics, the first, second and third serial connection circuits are parallel connected, the varactors 4 and 11 are connected to the connection side of the second and third serial connection circuit to mutually invert their directivity, the capacitance of the varactors 4 and 11 is changed by control from the outside and in accordance with the changed variable-capacitance, an oscillation frequency is determined. COPYRIGHT: (C)2004,JPO
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