The MULT is useful for shifting the phase-detector frequency to avoid integer boundary spurs. The multiplier allows a multiplication of 3, 4, 5, 6, or 7. There are some considerations when using the input multiplier:
- The programmable input multiplier cannot be used at the same time that the Input Path Doubler is used.
- The programmable input multiplier degrades the PLL figure of merit by about 8 dB; it is for spur mitigation, not PLL noise improvement.
- The programmable input multiplier is most effective when VCO frequency is not close to a multiple of the OSCIN frequency.