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？
% u$ s! g6 {5 V( b( j( O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)
    IC driver rise/fall time ..2.000 ns
1 ]9 h$ D; j* ]* {3 W; _    IC driver switching voltage range ..3.00 V
* |/ `' L% o3 `& |, F1 R1 U# K    IC driver output impedance 1.0 ohms
2 c6 s% z; |# J* l, d) p' d    IC input capacitance ..... 7.0 pF
串扰门限为
6 p& x0 q( a4 b% S5 \# s% RMaximum allowed crosstalk ........... 200 mv peak
特定看一个网络：
  NET = SOFT_TCK
   ELECTRICALLY ASSOCIATED NETS --------------------------------------
     None
+ o5 y' @4 `0 t( d  z, F   AGGRESSOR NETS (Estimated peak crosstalk)
7 X9 H& v' a8 p# Z3 a     NetFPGA1S_B22 .................. 233 mv
8 O" u& y0 q+ C4 R) c+ U     Total estimated crosstalk ....................... 233 mv
     ** Warning ** Estimate exceeds maximum allowed crosstalk!
# Y5 Y; A+ m- k" ^% V而我分配模型之后，该网络的串扰增加了很多：
  NET = SOFT_TCK
+ N/ C0 V1 P. a: j& r8 u0 R   ELECTRICALLY ASSOCIATED NETS --------------------------------------
     None
1 h, G: q2 x, [+ I   AGGRESSOR NETS (Estimated peak crosstalk)
4 j+ y/ Y; ^2 ]- t     NetFPGA1S_B22 ..................1268 mv
     NetFPGA1S_A21 ..................1053 mv
$ y1 i- G; `8 h1 ~     NetFPGA1S_A20 .................. 456 mv
     SOFT_TDI ....................... 319 mv
/ C& W$ Y$ q6 y     DIG5_SEG2 ...................... 227 mv
     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；