| 摘要 |
PURPOSE:To obtain the FSK receiver with low power consumption even when a PLL local oscillating circuit by monitoring out of synchronism to reduce a PLL operation time when no out of synchronism is caused. CONSTITUTION:A frequency detection circuit 110 monitors a state of carrier synchronization state and when the circuit 110 detects the occurrence of slight out of synchronism, the circuit 110 gives a detection signal to a control circuit 113. The control circuit 113 controls the PLL operation and when a detection signal from the frequency detection circuit 110 is not sent, since no shift takes place in the oscillated frequency of a PLL oscillation circuit 109, the PLL advanced operating time is discriminated to be short and reduced. So long as out of synchronism is detected, the PLL advance operation is implemented early. |
