| 摘要 |
The present invention, generally speaking, achieves noise spreading within a PLL using a dual-modulus prescaler(P, P+1) and two counters (R and Q) by interleaving the division moduli. Within a given cycle, "ones" and "tens" are not all counted consecutively. Instead, ones and tens are interleaved. In one embodiment of the invention, the R count is doubled and the output of the counter (R) is toggled between high and low states (the counter (Q) may remain unmodified). In another embodiment of the invention, ones and tens are interleaved in accordance with a ratio q:r. By so interleaving the modulus, the effect is to spread the noise resulting from the output signal of the dual-modulus prescaler over a wider frequency range. The prescaler noise level is greatly reduced, particularly within the frequency band of the reference frequency.
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