eldo_user

Working with S, Y, Z Parameters
Touchstone Data File Format
• [R Val|R1 Val1 ... Rn Valn]
Reference impedance of each port (when all the ports have the same reference impedance
you can specify a single value). Default value is all ports with the same 50 W reference
impedance.
Note
The two-port noise parameters (NFMIN, GAMMA_OPT_MAG, PHI_OPT, RNEQ) can be
included in the Touchstone data file when you have specified a .NOISE command in the
netlist and when the circuit to be analyzed is a two-port circuit. NFMIN is the minimal noise
figure of the two-port. GAMA_OPT is the magnitude of the optimal reflection coefficient
associated with the minimum noise figure. PHI_OPT is the angle of the optimal reflection
coefficient associated with the minimum noise figure. RNEQ is the equivalent noise resistance.
Examples
Touchstone data file option line example:
# khz s ri r 50
Frequency values are in kHz, the data is S parameter data, they are stored in the format Real and
Imaginary part, and the reference impedance is 50Ω for each port.
Example S parameters for three ports:
F
SR11 SI11 SR12 SI12 SR13 SI13
SR21 SI21 SR22 SI22 SR23 SI23
SR31 SI31 SR32 SI32 SR33 SI33
Two ports may be represented in matrix or single line format, but with a different parameter
order (S12 and S21 are swapped). For example:
Two ports in single line format:
Freq S11 S21 S12 S22
Two ports in matrix format:
Freq S11 S12
S21 S22
Mixed-Mode S Parameter Extraction
When extracting mixed-mode S parameters the contents of the Touchstone output data file
changes. For example the file header for a 2-port network may be as follows:
! Data from foo
! S11 = SDD11
! S12 = SDS12
! S13 = SDC11
# HZ S RI R1 1.000000E+01 R2 1.000000E+00
706
Eldo® User's Manual, 15.3