Patent ID: 8294527

Claim:
An oscillator circuit comprising: a current source; a resonant unit; an oscillation amplification unit connected to the current source while being connected in parallel to the resonant unit; a feedback resistor connected in parallel to the oscillation amplification unit; a bypass resistor having a resistance value lower than a resistance value of the feedback resistor; a switch unit connected between the feedback resistor and the bypass resistor, and configured to switch in the feedback resistor or the bypass resistor; and a control unit configured to control the switch unit such that a current from the current source is bypassed to the bypass resistor during a predetermined oscillation starting period after the current from the current source starts to be supplied to the resonant unit, and to control the switch unit such that the current from the current source flows to the feedback resistor after the predetermined oscillation starting period has ended, wherein the switch unit includes a plurality of bypass switch devices which are connected between a first end of the feedback resistor and a first end of the bypass resistor, and between a second end of the feedback resistor and a second end of the bypass resistor, and the control unit includes a charging section configured to charge a control terminal of the plurality of bypass switch devices from an initial voltage to a threshold voltage in a predetermined charging period that is greater than or equal to the predetermined oscillation starting period so that the plurality of bypass switch devices are switched from an on state to an off state after the predetermined oscillation starting period has ended.