| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor integrated circuit and a voltage control oscillator (VOC) capable of performing stable oscillating operation and generating an oscillation signal of a small jitter. SOLUTION: The semiconductor integrated circuit has a VCO cell 10a, a replica cell 11 constituted similarly as the VCO cell 10a, an operation amplifier 12 and a current source bias circuit 3. Between a node N1 and a ground terminal in the cell 10a, an NMOS transistor Q6 is connected and the replica 11 of the same structure as the cell 10a is provided to control the voltage of a node N1a in a replica cell 11 and the voltage of a node N1 in the cell 10a to be equal to reference voltage REF by the operation amplifier 12, thereby the voltage of the node N1 is nearly fixed even when the oscillation frequency of the VCO is varied. Thus, a PMOS transistor Q1 being a constant current source always operates in a pentrode area to stabilize oscillation operation. A CC jitter on the side of a low frequency can be reduced compared with a conventional system.
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