Circuit Elements

  1. Primitives
  2. Circuit Elements

mtline

mtline :
A multi-conductor, multi-port transmission line.

The mtline primitive models a multi-conductor, multi-port transmission line with a characteristic impedance of Z0 and propagation delay of delay. The port terminals of the M transmission lines are named as shown below:

pos_1[0], neg_1[0]     ----o======line #0======o---- pos_2[0], neg_2[0]
pos_1[1], neg_1[1]     ----o======line #1======o---- pos_2[1], neg_2[1]
                                    ...
pos_1[M-1], neg_1[M-1] ----o=====line #M-1=====o---- pos_2[M-1], neg_2[M-1]

where the number of transmission lines M is defined by the parameter num_line.

The real-array parameters ports and data together can define the frequency-dependent transfer characteristics between any selected source and destination ports of the transmission line. For instance, if the transmission or reflection coefficient from line L1, port P1 to line L2, port P2 can be described as the following s-domain transfer function H(s) having total of N partial fraction terms:

           b1_real + j*b1_imag                  bN_real + j*bN_imag
H(s) = ---------------------------- + ... + ---------------------------- ,
       (s + a1_real + j*a1_imag)^m1         (s + aN_real + j*aN_imag)^mN

the parameter ports shall contain the following entries for the source and destination port indices:

ports = '{ ..., L1.P1, L2.P2, ... }

where the port index takes a real value in the format of “<line index>.<port index>“. For example, the index for the port #2 of the line #1 is 1.2. And at the corresponding position, the parameter data shall have the 5*N+1 entries:

data = '{ ...,
         N,                                             // number of terms
         a1_real, a1_imag, b1_real, b1_imag, m1,        // partial fraction term #1
         a2_real, a2_imag, b2_real, b2_imag, m2,        // partial fraction term #2
         ...
         aN_real, aN_imag, bN_real, bN_imag, mN,        // partial fraction term #N
         ...
       }

The parameters ports and data can be alternatively defined by a parameter definition file named filename which defines the same named parameters in Python format. For any transmission characteristics not specified, the primitive assumes the reciprocal characteristics from the ones defined and ideal characteristics for the rest (i.e. no transmission loss and no crosstalk).

This primitive is a pseudo-module describing a structural netlist of electrical circuits and not a behavioral model by itself. The XMODEL simulator extracts an event-driven behavioral model at run-time based on the circuit network described by these circuit-level pseudo-modules.

Input/Output Terminals

Name I/O Type Description
pos_1 input xreal positive terminal of port #1
neg_1 input xreal negative terminal of port #1
pos_2 input xreal positive terminal of port #2
neg_2 input xreal negative terminal of port #2

Parameters

Name Type Default Unit Description
num_line int 1 None number of transmission lines
Z0 real 50.0 ohms characteristic impedance
delay real 0.0 seconds line propagation delay
ports real array ‘{0.0} None source/destination ports
data real array ‘{0.0} None transfer characteristics data
filename string ” “ None parameter definition file
abstol real 1e-3 None absolute tolerance for event-filtering
reltol real 1e-2 None relative tolerance for event-filtering
m real 1.0 None multiplicity factor
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