SNP

SNP- S-parameter model with vector fitting description.

Model for multi-port linear devices enables simulation in transient or CW mode, see Simcontroller.

Signal type: allows to configure the input signal as complex or real
Left ports: number of block's left ports
Right ports: number of block's right ports
Parallel instance: specify the number of model in parallel to simplify the design of large RF architecture
Model parameter file: specify the path to VISION model extracted from Device Modeler (*.head file), S-parameter touchstone file (*.sNp file) or parameterized touchstone format (*.dat file) (see corresponding section below)
Data type: type of data file description S parameters, Y parameters or Z parameters
Data format: specify the format that can be Touchstone (.sNp), VISION file (.head) or parameterized touchstone
- VISION file (.head)
  
  Figure: SNP block from VISION file
- Touchstone file (.sNp)
  
  Figure: Touchstone file
  - Interpolation method: interpolation can be performed thanks to cubic spline or vector fitting method. Note that the method cubic spline is only compatible with a CW simulation. For vector fittingmethod, the user has access to the following settings and options:
    - Save extracted model: option that if activated allows to save VISION model in simulation results' folder
    - Number of poles: user can specify 0 for automatic search or positive integer to fix pole/residu number
    - Pole fine tune: option that if activated tunes number of pole/residu from 1 to value specify in the previous parameter "Number of poles".
- Parameterized Touchstone
  Parameterized Touchstone data file format is a collection of regular Touchstone data files obtained for all points in the control parameter space. The touchstone file can be either encapsulated within a single data file called head file, or be maintained separated and referred into the main file. When touchstone files are maintained separated, they must be located in the same directory or subdirectory of the main file. Note that the number and frequency points values in all Touchstone blocks must be identical.
  The format is composed of a header indicating the block dimensions and a body containing Touchstone blocks or references to independent Touchstone file.
  Header
```
#NB_PORT = number of ports: Np
#NB_FREQ = number of frequency points: nb-F
#NB_PARAM = number of design parameters: P
#NB_PARAM_PTS = List of number of points per parameter: nb-1,..., nb-P

#PARAM$1 = val1-1, ..., val1-nb-1 : list of 1st parameter values
#PARAM$2 = val1-1, ..., val1-nb-1 : list of 2nd parameter values
...
#PARAM$P = valP-1, ..., valP-nb-P: list of Pth parameter values
```
  Body: Nested loop of encapsulated Touchstone blocks, following hierarchy param1, …, paramP. 2 possible options for touchstone block definition:
  - Encapsulated inline block within #BEGIN and #END statements
```
#BEGIN
    Touchstone format data for one control parameter space value
#END
```
  - External file reference preceded by #FILE statement
```
#FILE regular Touchstone-formatted data file name 
    (must be located in the same directory or subdirectory of the mail file)
```
  With this data format, user have access to the same options and parameters as before using a unique touchstone file. In addition, two parameters appear for parameterized touchstone file:
Control mode: user can choose between switch mode (discrete control parameter value) or continuous mode (interpolated S-parameter data)
Control parameter value: list of values or variables names to set control parameters (ex.: p1; p2; p3)

Parameterized Touchstone file examples can be found in VISION installation directory:

.\AMCAD Engineering\VISION\example\vision\data_example\Switch