| 摘要 |
A reference frequency generating section 10 capable of suitably changing frequency accuracy of an output signal in accordance with an input control voltage, and a high-accurate reference frequency generating section 13 having accuracy for a temperature change extremely higher than that of the reference frequency generating section 10 and in which output frequency accuracy thereof changes only within a range of prescribed values (frequency accuracy within a range where transmission and reception of a portable telephone can be conducted) are provided. A reference frequency after an AFC operation, which is output from the reference frequency generating section 10, is compared with an output signal from the high-accurate reference frequency generating section 13, and whether or not frequency accuracy of an output signal from the reference frequency generating section 10 meets a prescribed value is determined. In case of being met, a signal output from the reference frequency generating section 10 is used for a reference frequency. On the other hand, in case that the prescribed value is not met, a signal output from the high-accurate reference frequency generating section 13 is used for a reference frequency. |
