| 摘要 |
PURPOSE:To reduce power consumption and to attain the standby for a long time by using a local frequency obtained from a self-running frequency of a VCO of a frequency synthesizer circuit so as to implement a reception of a control channel in the standby state. CONSTITUTION:Changeover switches 20,21 of a frequency synthesizer circuit 17 are thrown respectively to the position (a) in the standby operation and a VCO 14 is free-running-oscillated by a voltage obtained from a bias circuit 22 and a 1st local frequency is generated to select a control channel. The control channel is turned by a mixer circuit 6 and an intermediate frequency BPF 7 by using the frequency and the input of a reception frequency is awaited. When a radio wave is inputted from an antenna 1, a high frequency signal tuned by the 1st local frequency is demodulated by a detection circuit 12 to be a low frequency signal, a control data is demodulated and outputted, and a discrimination output of the presence of a carrier is informed to a control circuit. When talking is finished and the standby operation is transited again, the changeover switches 20,21 are thrown to the position (a) to stop power supply of a PLL 15 and a crystal oscillation circuit 16 so as to reduce the current consumption of the reception circuit. |
