Hi All.. This is Ramana, can u guys,help me out..
                      i need to use Tx Line with following specs
 for a small length ∇ deltax, i know R, L,C,G & Rs(for skin effect) & Rd( for Dielectric loss).. then i don't know hw to use these things in spectre format..

   i mean, i was unable to calculate Z0, vel, f & electric length.. if i use formulae  for Z0= sqrt( (R+jwL)/(G+jwC) ) it will have complex part,

  Plz help me...

Thanks alot..
Ramana Akula

Hi Ken... Thanks alot for ur info. can U make sure the following specs in spice & spectre are equal & help me in these specfications..

In SPICE:-R, L, G, C, Rs, Gd & Physical Length of Tx Line are known. ( need to change into spectre format)

For Spectre:-     (1) Z0, vel are calculated using L & C(Loss less)
                          (2) len is same as physical length.
                          (3) dcr is same as R in Spice
                          (4) corner ??? ( help me here, hw to calculate in terms of above spice specs)
                          (5) g is same as G in Spice.
                          (6) hw to include Gd in Spectre ( like (alphad) or (fd & qd) specfication ????? )
   
     Please Help me..
Thanks Ken...
Ramana Akula...

Hi Ken.. Thanks for ur reply...  i was well understood what u said...
         (1) I'm using smart spice(SSpice) not HSpice..
         (2) the two conductances in spice are G (corresponds to parallel resistor in tx.model)  & Gd(corresponds to dielectric loss )
        in My SSpice deck, Tx. Line statement is
 W3 in1 in2  gnd out1 out2 gnd RLGCFILE=TLDATA.RLC  L=1
The file TLDATA.RLC will have values for R L G C Rs Gd parameters.see attachment.

 what i exactly need is corner frequency & alphad calculations..(Tx Line described in spice format i mean above spice statement & .RLC file)

Thanks Ken...
Ramana Akula..

The TLDATA.RLC file is:-
________________________________ file starts ___________________________________________


***************************************************************************
* RLGC parameters for two signal conductor
* lossy transmission line
***************************************************************************
* N - number of signal conductors
***************************************************************************
2  1
***************************************************************************
* 1 - Frequency
***************************************************************************
250E6
***************************************************************************
* L - indictance (nH/m)
***************************************************************************
613n
0.0   613n
***************************************************************************
* C - capasitance (pF/m)
***************************************************************************
56p
0.0   56p
***************************************************************************
* R - resistance (Ohm/m)
***************************************************************************
98e-3
0.0     98e-3
***************************************************************************

***************************************************************************
* G - DC conductance
***************************************************************************
0.1e-12  
0.0   0.1e-12
***************************************************************************
* Rs - Skin-effect resistance matrix per unit length
***************************************************************************
0.29e-3
0        0.29e-3
***************************************************************************
* Gd - Dielectric-loss conductance matrix per unit length
***************************************************************************
0.1e-3
0      0.1e-3
***************************************************************************
_____________________________ file Ends ______________________________

What you are after is "mtline" (see spectre -h mtline). This is a multi-line transmission line, which allows specification of RLGC matrices, and also has (in MMSIM60) a field solver built-in to generate the RLGC matrices from physical dimensions. It's similar to the W element in hspice and smartspice.

Regards,

Andrew.

spice result is:

Thanks Andrew & Mike..
         i got the reason( i think)...  we need careful look at units of spice & spectre.

For  Rskin ->  ohm / m                         for  spice  
                         ohm / ( m * sqrt(Hz) ) for spectre

For  gdloss ->  mho / m                         for  spice  
                         mho/ ( m *Hz )              for spectre

so if we take care this one we can get gud comparable results spice & spectre...

but i'm getting pblms when pulse is given as input..

 * If the time period of pulse is high enough, i mean usec's it'z giving gud results.  if the period is in the order of nano sec(10-20ns) it's giving abnormal response

My deck is:

-------------------------------------------- Deck starts -----------------------
// A simple Tx line terminated by 50ohm load with pulse input


simulator lang=spectre insensitive=yes

//  ********************************************************************************

//                              OPTIONS STATEMENT
//  ********************************************************************************


simulatorOptions options reltol=1e-5 vabstol=1e-6 iabstol=1e-12 temp=25 \
   tnom=27 scalem=1.0 scale=1.0 gmin=1e-12 rforce=1 maxnotes=5 maxwarns=5 \
   digits=5 cols=80 pivrel=1e-3 ckptclock=1800 \
   sensfile="sens.output"
//  ********************************************************************************


vgnd (gnd 0)  vsource dc=0

// *********** Input Signals....

// ***** sine
//vvin1 (in1 gnd)  vsource type=sine mag=10 ampl=10 freq=1M dc=0
//vvin2 (in2 gnd)  vsource type=sine mag=10 ampl=10 freq=1M dc=0

// ***** Unit Step
//vvin1 (in1 gnd)  vsource type=pwl wave=[0n 0 100n 0 110n 10 10m 10 10.00001m 0]
//vvin2 (in2 gnd)  vsource type=pwl wave=[0n 0 100n 0 110n 10 10m 10 10.00001m 0]

// ***** Pulse
//vvin1 (in1 gnd)  vsource type=pulse val0=0 val1=10 rise=5u fall=5u delay=0 width=10u period=30u                //working..

//vvin2 (in2 gnd)  vsource type=pulse val0=0 val1=10 rise=5u fall=5u delay=0 width=10u period=20u               //it's working...

vvin1 (in1 gnd)  vsource type=pulse val0=0 val1=10 rise=1n fall=1n
+ width=8n  period=16n  //it's not working...

vvin2 (in2 gnd)  vsource type=pulse val0=0 val1=10 rise=100n fall=100n delay=0 width=10u period=20u        //it's working...

vvin (in gnd)  vsource type=pulse val0=0 val1=10 rise=1n fall=1n
+ width=8n  period=16n   //it's not working...

// **************************
TL_mtline (in out gnd ) mtline len=100
+r= [ 98e-3 ]
+ l = [ 613n ]
+ g= [ 0.1e-12 ]
+c= [ 56p]
+ rskin= [ 0.1834e-6 ]
+ gdloss= [0.4e-12 ]
         

// ************

TL1 (in1 out1 in2 out2 gnd gnd) mtline len=100  
+ r= [ 98e-3 +     0.0     98e-3]
+
+ l = [ 613n+      0.0   613n]
+
+ g= [ 0.1e-12  +        0.0   0.1e-12]
+
+ c= [ 56p+      0.0   56p]
+
+ rskin= [ 0.1834e-6 +             0    0.1834e-6]
+
+ gdloss= [0.4e-12+          0    0.4e-12]
//rin1 (vin1 in) resistor r=50
//rin2 (vin2 in) resistor r=50
rout1 (out1 0) resistor r=50
rout2 (out2 0) resistor r=50
rout (out 0) resistor r=50


//  ********************************************************************************

//                                 ANALYSIS
//  ********************************************************************************

save=all oppoint=rawfile
analysis_ac1 ac dec=1000 start=1 stop=1G
tran1 tran step=1p stop=10m

//  ********************************************************************************

----------------- deck ends --------------------


 i'm also attaching the results. plz tell me the reason for abnormal response ( does reflections from load making the difference?????)
 
  AC response is also not gud.. i'm tring this for 100m category 5(CAT 5) UTP cable

Thanks to All,
Ramana...

Hi.. can u plz help me...

  tx.line AC response has some glicthes.. can u plz tell me the reason.
i'm attaching my deck & AC response plot.  

-------------- File --------
* Tx. Line
.options scale=1 accurate=1 rmax=1 RAWPTS=100 NUMDGT=16 probe expert

.temp 25
.save all

*------- INPUT'S...

*** Sine
VINP1 IN1 gnd ac=1
VINP2 IN2 gnd ac=1

*-------

RO1 OUT1 gnd 50
RO2 OUT2 gnd 50

W1 IN1  gnd OUT1  gnd RLGCFILE=TLDATA.RLC L=100
W2 IN2  gnd OUT2  gnd RLGCFILE=TLDATA.RLC L=1

.ac dec 100 0.1 1G

----------------- file ends --------------

TLDATA.RLC file :

----------------- .RLC file starts -----------------
***************************************************************************
* RLGC parameters for two signal conductor
* lossy transmission line
***************************************************************************
* N - number of signal conductors
***************************************************************************
1 1    
***************************************************************************
* 1 - Frequency
***************************************************************************
250E6
***************************************************************************
* L - indictance (nH/m)
***************************************************************************
613n

***************************************************************************
* C - capasitance (pF/m)
***************************************************************************
56p

***************************************************************************
* R - resistance (Ohm/m)
***************************************************************************
0.98e-3

***************************************************************************

***************************************************************************
* G - DC conductance
***************************************************************************
0.1e-12

***************************************************************************
* Rs - Skin-effect resistance matrix per unit length
***************************************************************************
0.29e-3

***************************************************************************
* Gd - Dielectric-loss conductance matrix per unit length
***************************************************************************
0.1e-3

***************************************************************************
---------- .RLC file ends  -----------------

 these are cat5 UTP cable specfications, i came across that freq response has shape of  decying exponential curve, but i'm getting Low pass filter curve.
can u plz provide me some info. regarding this..


                         waiting for ur positive response...
Thanks Alot ,
Ramana Akula