| 摘要 |
A frequency synthesizer with multiple tuning loops, e.g., a fine tuning loop and a coarse tuning loop, is described. The fine tuning loop may operate over a limited tuning range and may have fine frequency resolution. The coarse tuning loop may operate over a wide tuning range and may have coarse frequency resolution. The fine tuning loop may receive a reference signal at a reference frequency and generate a fine tuning signal at a first frequency adjustable in fine steps. The coarse tuning loop may receive the reference signal, generate an output signal at an output frequency, and generate a coarse tuning signal at a second frequency based on the output signal and the fine tuning signal. The second frequency may be adjustable in coarse steps, e.g., in integer multiples of the reference frequency. The output frequency may be determined based on the first frequency and the second frequency.
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