串扰问题？

lwenming

请问各位大虾，1、HyperLynx对PCB板做快速串扰分析时，需要加入器件IBIS模型吗？2、在加入IBIS模型之后，串扰的值一般是多大，不影响设计？
1 `: t/ V% Z& D& C( k* {. s& Q我在DXP下面找了个example,对其进行快速串扰分析时，不加如IBIS模型，采用默认的模型参数为
Board temperature ................ 20.0 degrees C
  Default IC model (used for quick analysis if IC model is missing)
  C( i% o2 i- q) \4 ^$ S& P) K    IC driver rise/fall time ..2.000 ns
    IC driver switching voltage range ..3.00 V
5 u/ P+ A3 K, y' o    IC driver output impedance 1.0 ohms
  H  I+ \$ v/ S! f4 C    IC input capacitance ..... 7.0 pF
串扰门限为
Maximum allowed crosstalk ........... 200 mv peak
) C* H1 y+ I7 R+ B特定看一个网络：
- o6 s- y3 H8 D0 R. P" y  NET = SOFT_TCK
9 Q0 R! f  s" V! N0 ]   ELECTRICALLY ASSOCIATED NETS --------------------------------------
4 x! O$ Y! O0 C8 s1 m4 ~8 m8 S) y+ t     None
( v" M! K$ g  h7 \8 i, B' a, ^   AGGRESSOR NETS (Estimated peak crosstalk)
( H" M8 o) X' F8 B# g3 ~     NetFPGA1S_B22 .................. 233 mv
+ {* R3 Y2 N' a+ w$ O     Total estimated crosstalk ....................... 233 mv
     ** Warning ** Estimate exceeds maximum allowed crosstalk!
9 O* W4 n% u- u! n而我分配模型之后，该网络的串扰增加了很多：
  NET = SOFT_TCK
! f( L3 l5 }* ]; _" u  W   ELECTRICALLY ASSOCIATED NETS --------------------------------------
1 B; _6 S+ \0 O, s- Y     None
   AGGRESSOR NETS (Estimated peak crosstalk)
     NetFPGA1S_B22 ..................1268 mv
     NetFPGA1S_A21 ..................1053 mv
     NetFPGA1S_A20 .................. 456 mv
8 Y' O8 F) t- h2 ^% \3 q     SOFT_TDI ....................... 319 mv
     DIG5_SEG2 ...................... 227 mv
  n  t# s/ j* x- R     Sum of the two strongest aggressors .............2321 mv
     ** Warning ** Estimate exceeds maximum allowed crosstalk!

kiddguan

需要加入模型，阈值一般可以通过简单计算得到.不同的电平，阈值是不同的，5v的10%=500mv,考虑串扰是500mv的30%=150mv；