Result Request

Analysis > Options > Solution Settings > Result Request

Introduction

The Result Request function has been added for Parasitics Extraction solution.

The Result Request allows the user to define the set of outputs for his study.

The Result Request dialog box is different for S-Parameter computation and Impedance computation.

List of Result Request for Parasitics Extraction solution


Result request		SimLab Solution
Result request		PE
S-Parameter Computation	Active Ports (All or Custom)
Touchstone Export	Create and Export a Touchstone File
	Frequency Unit
	Network Parameter Type
	Network Parameter Format
SPICE Export	Export in SPICE Format

Impedance Computation

The Result Request dialog box for Impedance Computation is the following:

Active Ports

In this part of the result request, the calculation of the Impedances can be done on All ports, or by choosing some of them by selecting the Custom case.

Note that if you select the Custom case, the self Impedance Z_ii will be computed only on the selected ports. The mutual Impedance Z_ij will be calculated with all the ports (with j represents the index of the active port). For example, in the figure below the self impedances that will be computed are Z₁₁ and Z₃₃, and the mutual impedances are Z₂₁ Z₃₁ Z₁₃ Z₂₃.

The short-circuited ports are not available in the result request for the impedance computation.

The resulting Impedance curves will be named following this convention: “Z-MAGNITUDE__Port1_Name Port2_Name” for the magnitude, and “Z_PHASE__ Port1_Name Port2_Name (deg)” for the argument.

Compute RLC values

This option allows to deduce Resistance (R), Inductance (L), and Capacitance (C) values from impedance (Z) value. In case of a frequency (f) sweep, the according RLC values are frequency dependent curves and can be seen in the 2DPlot. The computation is done as following:

When the option “Include Parasitic Capacitance effects” in Solver Settings is not selected, the C values will not be computed.

Note: Please note that the RLC values computed reflect the user-defined ports configuration. It is essential for the user to have a clear understanding of what he/she is going to compute according to the geometric connections of the ports. For example, if the user calculates capacitance values for a closed loop of electrical current, the resulting values may be inaccurate. Inversely, a computation of inductance values on an open loop can lead to its inaccuracy.

Examples:


Open Loop


Closed loop

S-Parameter Computation

The Result Request dialog box for S-Parameter Computation is the following:

In this part of the result request, the calculation of the S-Parameters can be done on All ports, or by choosing some of them by selecting the Custom case.

Note that if you select the Custom case, the reflection coefficients S_ii will be computed only on the selected ports. The transmission coefficients S_ij will be calculated with all the ports (with j represents the index of the active port). For example, in the figure below the reflection coefficients that will be computed are S₁₁ and S₃₃, and the transmission coefficients are S₂₁ S₃₁ S₁₃ S₂₃.

The resulting S-Parameter curves will be named following this convention: “S-MAGNITUDE__Port1_Name Port2_Name” for the magnitude, and “S_PHASE__ Port1_Name Port2_Name (deg)” for the argument.

Note: When the computation of S-Parameter is done on All ports, the solver computes the admittances Y (without the port resistances) and then convert them to S-Parameters using the write values for Z0 using this formula:

with:

[I] is the identity matrix.

[G₀] and [Z₀] are diagonal matrices (terms outside the diagonal are zero) where each term is related to a port reference impedance Z_n and :

This allows the well computation using Model Order Reduction, without considering the resistances of the ports which can introduce inaccuracies due to their high value compared to the interconnected parasites.

Note: Reference

T. Reveyrand, "Multiport conversions between S, Z, Y, h, ABCD, and T parameters," 2018 International Workshop on Integrated Nonlinear Microwave and Millimetre-wave Circuits (INMMIC), Brive La Gaillarde, France, 2018, pp. 1-3, doi: 10.1109/INMMIC.2018.8430023. keywords: {Scattering parameters;Impedance;Microwave devices;Mathematical model;Matrix converters;Scattering;Multiport;Embedding;De-embedding;S-parameters;Calibration;Education}

Touchstone Export

In this part of the result request, S-Parameters can be exported in conventional Touchstone format . The resulting file will have a .SnP extension, where n is the number of ports. For example: for three ports, the file extension will be .S3P.

Note that the Port numbers in the file exported are indexed based on the order in which they appear in the list of ports on the Loads and Constraints Browser tree, not on their labels.

The Touchstone file can be written using a specific frequency unit, from Hz to GHz using the Frequency Unit combo box. Scattering parameters are the only Network Parameter Type supported, Z-Parameters or others are not. For S-Parameters values, they can either be written in magnitude angle format or in real imaginary one. This can be done by choosing the appropriate format from the Network Parameter Format combo box. These settings do not affect 2D plotting curves in SimLab.

The reference impedance in the file is unique for all ports, this export does not support multi-reference impedances. The chosen impedance is that of the first port.

Note that the solution does not normalize the S-parameter values to a global reference impedance when exporting to Touchstone file. The values are referenced to the impedance specified on each port.

Note: Touchstone export is disabled if the Active Ports combo box is not in the All case for S-Parameter computation. This is motivated by the fact that we will have columns filled with zeros in the exported file on disabled ports, and zero remains a value, so it can be misleading.

SPICE Export

In this part of the result request, the S-parameters can be converted to a SPICE netlist and exported to a .subckt file in the Results folder. The SPICE model resulting uses an absolute port reference where each port is referenced to the SPICE global ground n0.

Note: This export only works in a Single-Ended port type configuration and Touchstone export must be checked.