| 摘要 |
<P>PROBLEM TO BE SOLVED: To shorten the time for frequency pull-in time at switching of a VCO, in a radio communications system provided with a PLL circuit having a plurality of VCOs. <P>SOLUTION: The frequency of a local oscillation signal, supplied from an oscillation system circuit, is varied according to the output voltage from a filter. The radio communications system comprises a receiving system circuit, combining the signal received from an antenna with the local oscillation signal, a set means of setting the predetermined voltage to the filter, in response to a second control signal, and a control means of generating a first control signal and generating the second control signal, according to the change in the local oscillation signal supplied from the oscillation system circuit and changed from a first frequency to a second frequency. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
