| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a frequency synthesizer not causing a problem of a filter while solving a problem of phase noise by employing a frequency offset type. <P>SOLUTION: An image rejection mixer 10 that offsets an oscillation frequency of a voltage controlled oscillator 1, is connected to the voltage controlled oscillator 1, and a frequency of an output signal of that image rejection mixer 10 is divided by a frequency divider 3, 4 and supplied to a phase comparator 8. Whereas, a reference signal generator 6 is provided to generate a reference frequency, and the output signal of the reference signal generator 6 or a reference signal of a phase comparison frequency fψ resulting from dividing the frequency of the above output signal is supplied to the phase comparator 8. In the phase comparator 8, a phase difference between the signal supplied from the frequency divider 3, 4 and the reference signal fψ is then detected and based on the phase difference, a control voltage is supplied to the voltage controlled oscillator 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
