| 摘要 |
<p>PURPOSE:To quickly transmit a response signal to an incoming signal even if a frequency synthesizer for transmission signal is intermittently operated during waiting, by providing a switch between a charge pump and a low-pass filter. CONSTITUTION:The intermitted operation that a switch 3 is turned on only for a time t2 is repeated with a period t1 (t1 is 2 sec. and t2 is 50msec.). A switch 43 is turned on after turning-on of the switch 3 and is turned off just before turning-off of the switch 3. In this case, a low-pass filter 44 is constituted to include a large-capacity capacitor, and the load of the filter 44 is the varactor capacitor diode of a VCO45 and its impedance is very high. As the result, the frequency of the transmission signal outputted from the VCO45 very approximates a normal frequency at the time of turning-on of the switch 3; and therefore, quick response to the incoming signal is possible even if the interruption frequency of a phase synchronizing loop is reduced.</p> |
