| 摘要 |
Disclosed is a semiconductor integrated circuit device that includes a ring oscillator circuit, performs a proper oscillation operation, and expands the range of oscillation frequency variation. The ring oscillator circuit includes, for instance, plural differential amplifier circuits. MOS transistors are respectively added to input nodes of a differential pair of the differential amplifier circuits. Further, gate control circuits are incorporated to control the gates of the MOS transistors, respectively. The gate control circuits cause the MOS transistors to function as an amplitude limiter circuit in mode 3, exercise control to turn off the amplitude limiter circuit in mode 2, and use the amplitude limiter circuit to start oscillation in mode 1.
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