>mag...@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 list: xapp210 xapp211 xapp217 xapp220 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 updated list: XAPP052 LFSR Generators N=3 to 168 http://www.xilinx.com/support/documentation/application_notes/xapp052.pdf XAPP210 LFSR in Vertix Devices http://www.xilinx.com/support/documentation/application_notes/xapp210.pdf XAPP211 PDF PN Generators Using The SRL Macro http://www.xilinx.com/support/documentation/application_notes/xapp211.pdf XAPP217 Gold Code Generators 77-42925.pdf http://application-notes.digchip.com/077/77-42925.pdf XAPP220 LFSRs As Functional Blocks in Wireless Applications http://uglyduck.ath.cx/PDF/Xilinx/Spartan3/appnotes/xapp220.pdf Mike Monett _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.