Hello,
In the datasheet it describes coefficient test mode as below,
>>>The Input to the decimating filter can be replaced with a sequence of "one impulse" and "zero" samples,
where "one impulse(that is 0x4000)" is followed by (16 x M) "zeros (that is 0 × 0000)".
However I got some confusing results by using test vectors provided in EVM package.
1.decimation factor=4, below is the original filter plot,
below is output of coefficient test mode which has been decimated by 4,
Question: how does the negative impulse response come from?
2.M=16 original filter
test result of coefficient test mode output which has been decimated by 16,
Additional question: how to explain the distance between response? In M=4, the distance is 64, however in M=16 the distance is 32.
And maybe the root question is: what's the real input sequence in coefficient test mode?
Thanks!
B.R.
River