4.2.5. PLL Cascading
Cyclone® V devices support two types of PLL cascading.
This cascading mode synthesizes a more precise output frequency than a single PLL in integer mode. Cascading two PLLs in integer mode expands the effective range of the pre-scale counter, N and the multiply counter, M.
Cyclone® V devices only use adjpllin input clock source for inter-cascading between fracturable fractional PLLs.
Altera recommends using a low bandwidth setting for the source (upstream) PLL and a high bandwidth setting for destination (downstream) PLL.
This cascading mode synthesizes a lower frequency output than a single post-scale counter, C. Cascading two C counters expands the effective range of C counters.
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