The gain control amplifier in order possesses

摘要

PPROBLEM TO BE SOLVED: To provide an oscillation circuit with simple configuration for materializing amplitude control in an oscillation loop with high accuracy, thereby decreasing an oscillation start time, and to provide a physical quantity transducer and a vibrating gyrosensor. PSOLUTION: The oscillation circuit 10 includes a gain control amplifier 20 which has a prescribed sensitivity characteristics indicating changes in the gain, with respect to a change in a control voltage Vc and controls the oscillation amplitude in an oscillation loop; and a gain control circuit 30 for outputting the control voltage Vc for adjusting the gain of the gain control amplifier 20 according to the oscillation amplitude. The gain control circuit 30 monitors the oscillation amplitude to discriminate whether the oscillation in the oscillation loop is in a steady-state or in a start-up process. When the gain control circuit 30 discriminates that the oscillation is in the start process, the gain control amplifier 20 changes the gain, according to the first sensitivity characteristics on the basis of the control voltage Vc; and when the gain control 30 discriminates that the oscillation is in the steady-state, the gain control amplifier 20 changes the gain, according to a second gain characteristics whose sensitivity is lower than that of the first sensitivity characteristics, on the basis of the control voltage Vc. PCOPYRIGHT: (C)2007,JPO&INPIT