Apr 5, 2006 #1 0 020170 Full Member level 4 Joined Jan 31, 2005 Messages 231 Helped 3 Reputation 6 Reaction score 1 Trophy points 1,298 Activity points 2,221 hspice lfsr LFSR is "linear feedback shift register" It is used to make pseudo random generator I'm afraid that this circuit is not working properly. all D output digital number is 0, it does not generate some codes in additional to, in my thought, It does not generate random codes, just shift codes from left to right. When I simulate this circuit, is there any thing I have to concern ? thanks
hspice lfsr LFSR is "linear feedback shift register" It is used to make pseudo random generator I'm afraid that this circuit is not working properly. all D output digital number is 0, it does not generate some codes in additional to, in my thought, It does not generate random codes, just shift codes from left to right. When I simulate this circuit, is there any thing I have to concern ? thanks
Apr 5, 2006 #2 F flushrat Full Member level 3 Joined Jan 25, 2005 Messages 180 Helped 23 Reputation 46 Reaction score 8 Trophy points 1,298 Activity points 1,532 hspice prbs You must set a non-zero seed, otherwise you will get all '0's. I use it to generate prbs data. There's no problem. If you need random data, suggest you to generate by program such as matlab, C...
hspice prbs You must set a non-zero seed, otherwise you will get all '0's. I use it to generate prbs data. There's no problem. If you need random data, suggest you to generate by program such as matlab, C...
Apr 5, 2006 #3 0 020170 Full Member level 4 Joined Jan 31, 2005 Messages 231 Helped 3 Reputation 6 Reaction score 1 Trophy points 1,298 Activity points 2,221 lfsr hspice thanks for your reply. I need prbs data but I'll get it by using hardware stuff like LFSR How do I insert initial seed into LFSR? I have to use modified LFSR like De Bruijn counter ? could you tell me where did you find it if you have some paper or document? thanks Another Question: LFSR is not truly ramdom signal, Pseudo random. But it doesn't look like pseudo random number. see the following picture it have about 1.0m period. what do I do to get enough long period? Thanks
lfsr hspice thanks for your reply. I need prbs data but I'll get it by using hardware stuff like LFSR How do I insert initial seed into LFSR? I have to use modified LFSR like De Bruijn counter ? could you tell me where did you find it if you have some paper or document? thanks Another Question: LFSR is not truly ramdom signal, Pseudo random. But it doesn't look like pseudo random number. see the following picture it have about 1.0m period. what do I do to get enough long period? Thanks
Apr 5, 2006 #4 F flushrat Full Member level 3 Joined Jan 25, 2005 Messages 180 Helped 23 Reputation 46 Reaction score 8 Trophy points 1,298 Activity points 1,532 hspice prbs "hspice simulation and analysis user guide" v2005.09 P190 lxxx n+ n- LFSR <(> vlow vhigh tdelay trise tfall rate seed <[> + taps <]> <rout=val> <)> For example this is a prbs7 with seed of all 1's. V1 n1 0 LFSR (0 1 td tr tr datarate 'pow(2,7)-1' [7, 6] )
hspice prbs "hspice simulation and analysis user guide" v2005.09 P190 lxxx n+ n- LFSR <(> vlow vhigh tdelay trise tfall rate seed <[> + taps <]> <rout=val> <)> For example this is a prbs7 with seed of all 1's. V1 n1 0 LFSR (0 1 td tr tr datarate 'pow(2,7)-1' [7, 6] )
Apr 7, 2006 #5 M meganathan Newbie level 3 Joined Sep 28, 2005 Messages 4 Helped 0 Reputation 0 Reaction score 0 Trophy points 1,281 Activity points 1,310 lfsr pspice Just u initialize one d ff o/p to 1 initially and then make it to work in normal operation
lfsr pspice Just u initialize one d ff o/p to 1 initially and then make it to work in normal operation
Apr 7, 2006 #6 M MSSN Full Member level 3 Joined Mar 8, 2006 Messages 157 Helped 37 Reputation 74 Reaction score 10 Trophy points 1,298 Activity points 2,300 prbs7 lfsr For the initial seed u can add logic that transfer u from state 0000 to 0001 for example ,and for long period u have to increase the number of FFs used
prbs7 lfsr For the initial seed u can add logic that transfer u from state 0000 to 0001 for example ,and for long period u have to increase the number of FFs used