[time-nuts] T.I. questions
timenuts at binsamp.e4ward.com
Sat Feb 7 21:40:35 EST 2015
>magnus at rubidium.dyndns.org said:
>> The typical noise generator chips uses a PRNG based on DFFs and XOR
>> gate(s). A typical weakness is that the chain of DFFs is to short, causing
>> a relatively high rate of cycling, which hearable as a beating. However, for
>> some uses, that is OK.
>The buzzword for the typical PRNG is LFSR - Linear Feedback Shift Register.
>Many years ago, Xilinx published a good app-note on this topic.
Several, in fact. I spent some time tracking them down. Here's the previous
But I found one more - XAPP052. It has a feedback table from N=3 to 168.
The table is repeated in later app notes. Also, Xilinx has apparently lost
XAPP217. It no longer appears on their web site, but I found it. Here's the
XAPP052 LFSR Generators N=3 to 168
XAPP210 LFSR in Vertix Devices
XAPP211 PDF PN Generators Using The SRL Macro
XAPP217 Gold Code Generators
XAPP220 LFSRs As Functional Blocks in Wireless Applications
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