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AR# 22256

LogiCORE Additive White Gaussian Noise (AWGN) - Why is there a timing ignore (TIG) for the top-level "sigma" path in the AWGN ".ucf" file?

Description

Why is there a timing ignore (TIG) for the top-level "sigma" path in the AWGN ".ucf" file?

Solution

The "sigma" path comes from a block RAM-based lookup table that maps the Signal to Noise Ratio (SNR) in dB to a linear scale (the standard deviation). Most users set the SNR to a value and then run the core for many cycles. Therefore, the SNR input is treated as static and the timing from the "sigma" path is not critical. That is why it is ignored using the TIG constraint.

For a detailed list of LogiCORE Additive White Gaussian Noise Generator (AWGN) Release Notes and Known Issues, see (Xilinx Answer 30171).

AR# 22256
Date Created 09/04/2007
Last Updated 12/15/2012
Status Active
Type General Article