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[求助] tline的参数

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发表于 2015-4-22 10:55:14 | 显示全部楼层 |阅读模式

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请教各位一下,cadence中tline具体参数中的frequency指的是什么频率啊,小弟第一次用tline。
发表于 2017-5-31 03:02:09 | 显示全部楼层
回复 1# 曹明喜


     spectre -h tline

*****************
Transmission Line
*****************

Lossy or lossless transmission line.

                  |-----------------|                 
   t1 -o----------|                 |-----------o- t2
       +   I1 ->  |                 |  <- I2    +     
       V1         |      tline      |           V2   
       -   I1 <-  |                 |  -> I2    -     
   b1 -o----------|                 |-----------o- b2
                  |-----------------|                 

The lossy transmission line model includes dielectric and conductor loss
effects. The conductor loss includes skin effect assuming finite or infinite
conductor thickness.

Only the odd mode is modeled, so only the voltage difference across each port
is important. (The absolute voltage of each terminal is not significant.)
Also, the current into one node of a port exactly equals the current leaving
the other node of the port.


Sample Instance Statement:
t1 (1 0 2 0) lmodel z0=100

Sample Model Statement:
model lmodel tline f=10M z0=50 alphac=8501 fc=10M dcr=88

This device is supported within altergroups.

Synopsis:
Name ( t1 b1 t2 b2 ) ModelName <parameter=value> ...
Name ( t1 b1 t2 b2 ) tline <parameter=value> ...

Model Synopsis:
model ModelName tline <parameter=value> ...


===================
Instance Parameters
===================

1       z0=50 Ohm         Characteristic impedance of lossless line.
2       td (s)            Time delay of a lossless line in seconds, a measure
                          of the electrical length.
3       f (Hz)            Reference frequency (used in conjunction to the
                          normalized length to specify electrical length of
                          line).
4       nl=0.25           Normalized electrical length in wavelengths at `f' of
                          a lossless line.
5       vel=1             Propagation velocity of the line given as a multiple
                          of `c', the speed of light in free space. (vel <=
                          1).
6       len=0 m           Physical length (used with `vel' to specify
                          electrical length of line).
7       m=1               Multiplicity factor.

Conductor loss parameters:
8       corner=0 Hz       Corner frequency for skin effect, frequency where
                          skin depth equals the conductor's wall thickness.
9       dcr=0 Ohm/m       DC series resistance per unit length.
10      fc (Hz)           Conductor loss measurement frequency (use with `r',
                          `qc', or `alphac').
11      r=0 Ohm/m         Conductor (series) resistance per unit length at
                          `fc'.
12      alphac=0 dB/m     Conductor loss at `fc' (low loss approximation).
13      qc=infinity       Conductor loss quality factor at `fc' (low loss
                          approximation).

Dielectric loss parameters:
14      fd (Hz)           Dielectric loss measurement frequency (use with
                          `qd').
15      g=0 S/m           Dielectric (shunt) conductance per unit length.
16      alphad=0 dB/m     Dielectric loss (low loss approximation).
17      qd=infinity       Dielectric loss quality factor at `fd' (low loss
                          approximation).

================
Model Parameters
================

1       z0=50 Ohm         Characteristic impedance of lossless line.
2       f (Hz)            Reference frequency (used in conjunction to the
                          normalized length to specify electrical length of
                          line).
3       vel=1             Propagation velocity of the line given as a multiple
                          of `c', the speed of light in free space. (vel <=
                          1).

Conductor loss parameters:
4       corner=0 Hz       Corner frequency for skin effect, frequency where
                          skin depth equals the conductor's wall thickness.
5       dcr=0 Ohm/m       DC series resistance per unit length.
6       fc (Hz)           Conductor loss measurement frequency (use with `r',
                          `qc', or `alphac').
7       r=0 Ohm/m         Conductor (series) resistance per unit length at
                          `fc'.
8       alphac=0 dB/m     Conductor loss at `fc' (low loss approximation).
9       qc=infinity       Conductor loss quality factor at `fc' (low loss
                          approximation).

Dielectric loss parameters:
10      fd (Hz)           Dielectric loss measurement frequency (use with
                          `qd').
11      g=0 S/m           Dielectric (shunt) conductance per unit length.
12      alphad=0 dB/m     Dielectric loss (low loss approximation).
13      qd=infinity       Dielectric loss quality factor at `fd' (low loss
                          approximation).

-------------
Lossless Case
-------------
The lossless transmission line is specified with parameters `z0' and `td'. The
device behavior is then:

       V1(t) - z0*I1(t) = V2(t-td) + z0*I2(t-td)
and
       V2(t) - zO*I2(t) = V1(t-td) + z0*I1(t-td).

where t is time and `td' is the delay. Note, if the device is terminated by a
matched impedance of `z0'( across t2 and b2), then it becomes an ideal delay.
i.e V2(t) = V1(t-td).

--------------------------------
To model both even and odd modes
--------------------------------
Use two lines as shown below.

                      tline_inner                       
                   |---------------|                    
     i1------------|    z0_inner   |--------------i2   
                   |    td_inner   |                    
               ----|---------------|-------            
               |                          |            
     o1--------|      tline_outer         |-------o2   
               |   |---------------|      |            
               ----|    z0_outer   |-------            
                   |    td_outer   |                    
         ----------|---------------|--------------      
         |                                       |      
        gnd                                     gnd     

This model is suitable for a coax where tline_inner models the inner/outer
conductor line (or the odd mode) while tline_outer models the outer/ground line
(or the even mode). Note that this model is non-symmetric.

----------
Lossy Case
----------
In the frequency-domain the device is modeled by

       V1(jw) - Z(jw)*I1(jw) = S12(jw)* [V2(jw) + Z(jw)I2(jw)]
and
       V2(jw) - Z(jw)*I2(jw) = S21(jw)* [V1(jw) + Z(jw)I1(jw)]

where j=sqrt(-1) and w is the angular frequency in radians/s. The loss
coefficient is computed from

       S21(jw) = S12(jw) = exp(-Gamma(jw)*len)
where
       Gamma(jw) = sqrt( Zc(jw) * Yd(jw) )

where Zc represents the per-unit-length series impedance and Yd represents the
per-unit-length shunt admittance loss (as described below). The characteristic
impedance (Z) is computed from

       Z(jw) = sqrt( Zc(jw) / Yd(jw) ).

The time-domain behavior of the lossy transmission line is computed through a
recursive convolution algorithm.

The dielectric loss (Yd) is computed from

       Yd(jw) = G + j* w/(z0*c*vel)

where G is the per-unit-length shunt conductance and can be specified in three
ways.

  1)   G = g                         { when `g' is given }
  2)   G = 2/z0 * alphad             { when `alphad' is given }
  3)   G = 2/z0 * fd/(2*qd*c*vel)    { when `fd' and `qd' are given }

where  `c' is the speed of light.

The series impedance (Zc) is computed from

       Zc(jw) = Zi + j*w*z0/(c*vel).

where Zi represents the internal loss. When skin effect is not present then

       Zi = dcr

where `dcr' is the DC series per-unit-length resistance.

Skin effect assuming finite thickness.

-------------------------------------
In this case the internal impedance (Zi) is computed from

       Zi = Ri + j*w*Li

where Ri and Li exhibit the following behavior

   Ri                                  Li                             
    |                        **         |                             
    |                    ****         L0|********                     
    |               *****               |        **                  
    |         ******                    |          *                  
dcr|*********                          |           **               
    |                                   |             **********      
    ----------|------------------       ----------|-------------****  
           W_corner           (freq)           W_corner         (freq)

The expressions for Ri and Li are

  when w << W_corner:   Ri ~ dcr      and       Li ~  dcr/(1.5*W_corner)

  when w >> W_corner:   Ri ~ dcr*sqrt(w/W_corner)
                    and
                        Li ~ dcr/(sqrt(w*W_corner))

  Otherwise: Ri = dcr * nt * (sinh(2*nt)+sin(2*nt))/(cosh(2*nt)-cos(2*nt))
         and
             Li = dcr * nt * (sinh(2*nt)-sin(2*nt))/(cosh(2*nt)-cos(2*nt)) / w
         where nt=sqrt(w/W_corner) is the normalized thickness

The equations can be found in:

Ramo, Whinnery, Van Duzer. Fields and waves in communication electronics. 1965.
See Section on "Impedance of thin-walled conductors". Pg 301.

The corner frequency (W_corner) results from skin effect on conductors of
finite thickness. As frequency decreases, skin depth increases resulting in
more conductor to pass the current, which results in lower loss. However, at
the corner frequency, the skin depth equals the radius of the conductor.
Decreasing the frequency below that point does not further reduce the loss.

The corner frequency (W_corner) can be specified in two ways.

  1) When `dcr' and `corner' are given, then

            W_corner= 2*pi*corner.

  2) When `dcr', `r', and `fc' are given, then

        W_corner = 2*pi*fc* (dcr/r)^2


In addition, there are two alternative ways to specify `r'.

  1) r = 2*z0*alphac             { when 'alphac' is given }
  2) r = 2*z0*fc/(2*qc*c*vel)    { when `qc' is given }

where 'c' is the speed of light are defined below.

Skin effect assuming infinite thickness
----------------------------------------
In this case there is no corner frequency (and no `dcr'), and the internal loss
(Zi) is computed from

       Zi= Ri + j*w*Li

where  Ri = r*sqrt(w/(2*pi*fc))  and  Li = r/sqrt(w*2*pi*fc).

Again, `r' can be specified directly, or using `alphac' or `qc' as described
above in the case of finite thickness.

---------------------------------------------
Three ways to specify `vel', `td', and `len'
---------------------------------------------
1) When `vel' and `len' are given

       td = len/(vel*c)

2) When `td' and `vel' are given

       len = td*vel*c

3) When `f', `nl' and `vel' are given

      td = nl/f
      len = (nl/f)*vel*c

The parameter `len' is the physical length, `c' is the speed of light and `vel'
is the propagation velocity as a multiple of `c' (Recall that velocity =
c/sqrt(relative dielectric constant)). The parameter `f' is a reference
frequency and `nl' is the normalized electrical length in wavelengths at `f'.



===============
Parameter Index
===============

    alphac .... I-12   f .......... I-3   len ........ I-6   r .......... M-7
    alphac ..... M-8   f .......... M-2   m .......... I-7   td ......... I-2
    alphad .... I-16   fc ........ I-10   nl ......... I-4   vel ........ I-5
    alphad .... M-12   fc ......... M-6   qc ........ I-13   vel ........ M-3
    corner ..... I-8   fd ........ I-14   qc ......... M-9   z0 ......... I-1
    corner ..... M-4   fd ........ M-10   qd ........ I-17   z0 ......... M-1
    dcr ........ I-9   g ......... I-15   qd ........ M-13
    dcr ........ M-5   g ......... M-11   r ......... I-11
发表于 2024-9-30 16:20:47 | 显示全部楼层


前辈好,请问说明首项中的仅对奇数模式建模的意思是只能是奇数条line吗?如果是差分传输线的tline该怎么办呢?
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