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AR# 55109

LogiCORE IP LTE Fast Fourier Transform v1.0 - Why is there a mismatch between C model and HDL on the overflow output when using the Pipelined, Streaming I/O architecture with user-defined scaling?

Description

The LTE FFT can occasionally give a mismatch between C model and HDL on the overflow output when using the Pipelined, Streaming I/O architecture with user-defined scaling.

The overflow (OVFLO0) output of the Pipelined, Streaming I/O architecture can occasionally not match the C model output.  The C model behavior is always correct.  Note that when overflow occurs in the Pipelined, Streaming I/O architecture, the output data will not match that from the C model, due to differing order of operations in each model.

Solution

To work around this issue, it is recommended to use a conservative scaling schedule (see documentation) which avoids overflow for all possible input data values. Where possible, the C model should be used in system simulations to verify overflow behavior and ensure overflow rates match the expected system requirements.

Linked Answer Records

Master Answer Records

AR# 55109
Date Created 03/25/2013
Last Updated 09/16/2013
Status Active
Type General Article
IP
  • LTE Fast Fourier Transform