| 摘要 |
PROBLEM TO BE SOLVED: To provide a crystal oscillator which does not prevent miniaturization and can improve phase noise characteristic.SOLUTION: A crystal oscillator comprises an oscillation circuit 31 having a transistor Q1 for oscillation, and an amplification circuit 32 having a transistor Q2 for amplification. The oscillation circuit 31 and the amplification circuit 32 have ceramic capacitors. The crystal oscillator also comprises a sensor 33 generating noise equivalent to that of ceramic capacitors used in the oscillation circuit 31 and the amplification circuit 32 under a vibration environment, and an operational amplifier 34 for inputting an output from the sensor 33 and performing phase inversion amplification, and the output from the operational amplifier 34 is connected to a base of the transistor Q2 for amplification. The crystal oscillator can cancel the noise generated from the ceramic capacitor in a high frequency circuit by inverting the noise equivalent to that generated from the sensor 33 and combining with the amplification circuit 32, and does not prevent miniaturization. |
