ZHCSE74C September 2015 – May 2025 LMK61E2
PRODUCTION DATA
These spurs occur at multiples of fPD/DEN and are not the integer boundary spur. For instance, if the phase detector frequency is 100MHz and the fraction is 3/100, the primary fractional spurs are at 1MHz, 2MHz, 4MHz, 5MHz, 6MHz, and so forth. These are impacted by the loop filter bandwidth and modulator order. If a small frequency error is acceptable, then a larger equivalent fraction can improve these spurs. This larger inequivalent fraction pushes the fractional spur energy to much lower frequencies to reduce impact on the system performance.