| 摘要 |
A frequency generation device (100) comprises a cascade of two phase-locked loops (104 and 108). The first PLL (104) is a frequency synthesizer while the second PLL, or offset loop (108), comprises a phase detector (208 or 306), loop filter (210 or 310), VCO (212 or 312) and a divider with near-unity modulus (204 or 308). In the case of a negative offset design, the near-unity divider (204) is placed in the offset loop feedback path. In a positive offset design, the near-unity divider (308) is placed in the path between the synthesizer VCO and the offset loop phase detector. Unlike existing art, there is no offset signal input to the second or offset loop (108).
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