skrf.network.Network.se2gmm

Network.se2gmm(p, z0_mm=None, s_def=None)[source]

Transform network from single ended parameters to generalized mixed mode parameters [1].

Parameters:

  • p (int) – number of differential ports

  • z0_mm (Numpy array) – f x 2*p x 2*p matrix of mixed mode impedances, optional. If input is None, 2 * z0 Ohms differential and z0 / 2 Ohms common mode reference impedance is used, where z0 is average of the differential pair ports reference impedance. Single-ended ports not converted to differential mode keep their z0.

  • s_def (str -> s_def : can be: 'power', 'pseudo' or 'traveling') – Scattering parameter definition : None to use the definition set in the network s_def attribute. ‘power’ for power-waves definition [2], ‘pseudo’ for pseudo-waves definition [3]. All the definitions give the same result if z0 is real valued.

  • Ports (Note Odd Number of) – In the case where there are an odd number of ports (such as a 3-port network with ports 0, 1, and 2), se2gmm() assumes that the last port (port 2) remains single-ended and ports 0 and 1 are converted to differential mode and common mode, respectively. For networks in which the port ordering is not suitable, port renumbering can be used.

Return type:

None

Examples

For example, a 3-port single-ended network is converted to mixed-mode parameters:

| Port 0 (single-ended, 50 ohms) --> Port 0 (single-ended, 50 ohms)
| Port 1 (single-ended, 50 ohms) --> Port 1 (differential mode, 100 ohms)
| Port 2 (single-ended, 50 ohms) --> Port 2 (common mode, 25 ohms)

>>> ntwk.renumber([0,1,2], [2,1,0])
>>> ntwk.se2gmm(p=1)
>>> ntwk.renumber([2,1,0], [0,1,2])

In the resulting network, port 0 is single-ended, port 1 is differential mode, and port 2 is common mode.

In following examples, sx is single-mode port x, dy is differential-mode port y, and cz is common-mode port z. The low insertion loss path of a transmission line is symbolized by ==.

2-Port diagram:

  +-----+             +-----+
0-|s0   |           0-|d0   |
  |     | =se2gmm=>   |     |
1-|s1   |           1-|c0   |
  +-----+             +-----+

3-Port diagram:

  +-----+             +-----+
0-|s0   |           0-|d0   |
1-|s1   | =se2gmm=> 1-|c0   |
2-|s2   |           2-|s2   |
  +-----+             +-----+

Note: The port s2 remain in single-mode.

4-Port diagram:

  +------+               +------+
0-|s0==s2|-2           0-|d0==d1|-1
  |      |   =se2gmm=>   |      |
1-|s1==s3|-3           2-|c0==c1|-3
  +------+               +------+

5-Port diagram:

  +------+               +------+
0-|s0==s2|-2           0-|d0==d1|-1
1-|s1==s3|-3 =se2gmm=> 2-|c0==c1|-3
  |    s4|-4             |    s4|-4
  +------+               +------+

Note: The port s4 remain in single-mode.

8-Port diagram:

  +------+               +------+
0-|s0==s2|-2           0-|d0==d1|-1
1-|s1==s3|-3           2-|d2==d3|-3
  |      |   =se2gmm=>   |      |
4-|s4==s6|-6           4-|c0==c1|-5
5-|s5==s7|-7           6-|c2==c3|-7
  +------+               +------+

2N-Port diagram:

     A                                  B
     +------------+                     +-----------+
   0-|s0========s2|-2                 0-|d0=======d1|-1
   1-|s1========s3|-3                 2-|d2=======d3|-3
    ...          ...     =se2gmm=>     ...         ...
2N-4-|s2N-4==s2N-2|-2N-2           2N-4-|cN-4===cN-3|-2N-3
2N-3-|s2N-3==s2N-1|-2N-1           2N-2-|cN-2===cN-1|-2N-1
     +------------+                     +-----------+

Note: The network A is not cascadable with the ** operator along transmission path.

References

See also

gmm2se