| 摘要 |
The invention relates to a frequency synthesizer, especially for mobile radio base stations, which transforms a digital input signal having a first frequency rapidly into a digital output signal having a second frequency. Similar to an N-fractional synthesizer, in the inventive frequency synthesizer the digital input signal is fed to a series connection consisting of a phase detector, a filter and a voltage-controlled oscillator. An essential feature of the invention is that the conventional N/N+1 divider provided in the feedback path, as in an N-fractional synthesizer, is replaced by some sort of digital synthesizer that is clocked or supplied with the digital output signal that is produced by the voltage-controlled oscillator.
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