| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a frequency synthesizer appropriate for a wireless system which performs frequency hopping. <P>SOLUTION: The frequency synthesizer has a phase comparator 8 and a charge pump circuit 9 for injecting an electric charge, or pulling it that corresponded to a frequency difference of an input, a low-pass filter 11 for converting this electric charge into a voltage, a voltage controlled oscillator (VCO) 13 for changing an output frequency for this input voltage, a divider 14 for dividing the frequency of the input, and a voltage holding circuit 10 for holding the input voltage for a plurality of output frequencies of the VCO. A holding voltage of the voltage holding circuit 10 is switched with a switch 12, and the frequency of an output clock signal 3 is switched. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
