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.

N_{MAX}
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.

S_{MAX}
must be set according to the following
equation.

The NIDRU configuration can be changed during run time. Different configurations can have
different N_{MAX}
. S_{MAX}
must be selected so that the previous equation is true for all configurations.

S_{MAX_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 S_{MAX}
, S_{MAX_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.