Logic Optimization

Non-Integer Data Recovery Unit (XAPP1362)

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The NIDRU performs many run-time calculations. The precision of these calculations can be controlled by attributes, which can be used to trade off between precision and resource usage.

MASK_CG = 1111111111111111 means internal 16 bit precision.

MASK_CG = 1111111111111110 means internal 15 bit precision.

The same is true for MASK_PD and MASK_VCO.

Lowering the precision can be done to reduce resources and should be evaluated by simulation or in hardware. If in doubt, set MASH_CG, MASK_PD, and MASK_VCO to all ones.

NMAX is the maximum number of samples extracted during one clock cycle. This parameter, defined in the following equation, is the reference to define the minimum value for other attributes of the NIDRU.

SMAX must be set according to the following equation.

The NIDRU configuration can be changed during run time. Different configurations can have different NMAX . SMAX must be selected so that the previous equation is true for all configurations.

SMAX_EYE is an internal parameter and has to be set according to the following equation.

WDT_OUT is the output width of the NIDRU and should be set according to the following equation.

Setting SMAX , SMAX_EYE , and WDT_OUT above their minimum values has no impact on the functionality of the NIDRU, and only results in slightly more usage of resources.