| 摘要 |
PROBLEM TO BE SOLVED: To obtain a voltage-controlled oscillation circuit that can have stable oscillation characteristics even if a CMOS process is changed and can facilitate the design for reducing jitter when applied to a PLL circuit. SOLUTION: A correction circuit 2 controls a PMOS transistor 15a so that an oscillation control current Ia to be supplied to a ring oscillator circuit 63 can be reduced, under conditions when the output frequency of the ring oscillator circuit 63 becomes higher than a desired frequency according to variations in a manufacturing process; and controls an NMOS transistor 15a so that the oscillation control current Ia supplied to the ring oscillator circuit 63 can be increased under conditions, when the output frequency of the ring oscillator circuit 63 becomes lower than the desired frequency. COPYRIGHT: (C)2006,JPO&NCIPI
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