Lossless Transmission Line

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Model Kind

Transmission Line

Model Sub-Kind

Lossless

SPICE Prefix

T

SPICE Netlist Template Format

@DESIGNATOR %1 %2 %3 %4 Z0=@"CHAR. IMPEDANCE" ?"TRANSMISSION DELAY"/TD=@"TRANSMISSION DELAY"//F=@FREQUENCY ?"NORMALISED LENGTH"|NL=@"NORMALISED LENGTH"|/ ?"INITIAL VOLTAGE 1"|IC=@"INITIAL VOLTAGE 1", @"INITIAL CURRENT 1", @"INITIAL VOLTAGE 2", @"INITIAL CURRENT 2"|

Parameters (definable at component level)

The following parameters are definable for this model type and are listed in the Parameters tab of the Sim Model dialog. To access this dialog, simply double-click on the entry for the simulation model link in the Models region of the Component Properties dialog.

Char. Impedance

-

characteristic impedance (in Ohms). (Default = 50).

Transmission Delay

-

Transmission delay (in seconds). (Default = 10n).

Frequency

-

frequency (in Hertz).

Normalised Length

-

normalized electrical length of the transmission line with respect to the wavelength in the line, at the specified frequency.

Port 1 Voltage

-

time-zero voltage at port 1 of the transmission line (in Volts).

Port 1 Current

-

time-zero current at port 1 of the transmission line (in Amps).

Port 2 Voltage

-

time-zero voltage at port 2 of the transmission line (in Volts).

Port 2 Current

-

time-zero current at port 2 of the transmission line (in Amps).

Notes

The length of the line must be expressed in one of the following two ways:

If a frequency is specified but a value for the Normalised Length is omitted, then 0.25 is assumed (that is, the frequency is assumed to be the quarter-wave frequency).

The values for Port 1 and Port 2 Initial Voltages and Currents only apply if the Use Initial Conditions option is enabled in the Transient/Fourier Analysis Setup page of the Analyses Setup dialog.

The simulation-ready lossless transmission line component (LLTRA) can be found in the Simulation Transmission Line integrated library (\Program Files\Altium\Library\Simulation\Simulation Transmission Line.IntLib).

Examples

Consider the lossless transmission line in the above image, with the following characteristics:

the entry in the SPICE netlist would be:

*Schematic Netlist:

TLLTR1 IN 0 OUT 0 Z0=50 TD=20NS

Links

The Netlist Template - Explained

SPICE3f5 models

Simulation Models