Working with Data Files

Data files are ASCII text representations of circuit responses based on various settings of independent variables. For instance the S-parameter response of an amplifier can be captured against frequency and power variations in a .p2d data file. Some ADS components, such as the AmplifierP2D_Setup and AmplifierS2D_Setup help create data files. Other sources for data files are measurement instruments or other simulation tools which output circuit responses in text form. Thus data files enable you to take data from sources outside of Advanced Design System or RF Design Environment and apply it to projects within these design environments.

The common purpose of all the various applications which require the use of data files, is to generate the behavior of a specific component or a circuit based on simulated or measured data points. Thus, data files allow the transfer of realistic parameter values to simple components and also enable the modeling of components with complex behavior such as black box and gray box models. Some examples of the use of data files are:

• Using S-parameters to define the behavior of a linear black-box component representing an attenuator, a filter, or a small-signal transistor. The S-parameters, which are saved in a file, are used in conjunction with a component like the S2P. This permits the creation of a realistic and customized 2-port network during an ADS simulation.
• Storing sets of transistor model parameters in separate files, and accessing them automatically through the course of a simulation to define the behavior of the transistor.
• Defining the behavior of a complex nonlinear amplifier by using the gray-box AmplifierS2D component and data saved in an S2D file. The small and large signal S-parameters as well as noise parameters contained within the file can be used to define the behavior of the amplifier during a simulation.

Besides data-file driven components, there are other user-defined models such as using SDDs, FDDs, equation-based components, or the Model Builder which are discussed elsewhere. This section focuses on how to use the various types of data files to define the behavior of components and circuits in addition to providing a comprehensive understanding of the classification and formats associated with the various types of data files used by various components.

A data file is simply data in an ASCII text file, but there are several formats to choose from depending on the application. When determining the type of data file to choose please note:

• The format you choose may depend on the type of data you have and where you want to use the data. The table below lists supported file formats and examples of where they are used.
• The DataAccessComponent may be used to access the data from any data file regardless of format and to use it with any component that accepts file-based parameters. In this case, you need to make sure there is a logical relationship between the data and how you intend to use it. For more information, see Using Data Files, Datasets, and Data Access Components.

Supported Data Formats

The following table lists the supported data formats with a brief description and a reference to detailed information:

Available File Format Types

For information about a particular component, refer to the documentation for Analog/RF or Signal Processing components, or click Help when editing component parameters.

Making a Data File

You can create a data file using these methods:

• Manually type the data into a text file using any text editor, being sure to follow the formatting guidelines for the type of data file that you want.
• Use the Data File Tool. The Data File Tool enables you to transfer data between datasets and files that are in the following file formats: Touchstone, Measurement data interchange format (MDIF), CITIfile, and IC-CAP. For learn about the Data File Tool, see Reading and Writing Data Files.
• Perform a P2D controller-based simulation using AmplifierP2D_Setup or AmplifierS2D_Setup. The results of these simulations are saved to files in P2D and S2D formats respectively, which can then be used with the AmplifierP2D or AmplifierS2D. For more information on the P2D controller itself, see P2D Simulation.

Saving a Data File

When saving a data file, save it as an ASCII text file.

• A data file does not require a particular extension, but you may want to use the extension recommended for each format for identification purposes. These extensions are given in the details describing each format. If you choose a different extension, you must provide this information to the component you intend to use through the File parameter of the component.

You can save the data file:

• In the project where it is used under the <prj>/data directory. This is the default location if no path is provided to the component using the file.
• Any location, if you provide the full file path to the component. You provide this information using the File parameter of the component.

For more information about the File parameter, place the component of interest on a schematic, double-click to edit it, and click the Help button at the bottom of the dialog box.

Using Data Files, Datasets, and Data Access Components

Both data files and datasets can contain data that you want to use with a component. You can use either one, depending on your situation:

• You may want the S-parameters from a simulated design. In this case, use the dataset and a DAC to link the data to the component you want to use.
• You may have S-parameter specifications from a component sheet. In this case, type them into a data file.

You also want to consider the method of linking your data with the component of interest:

• You have a data file, such as an .s2d, and you want to use it with a component that can read such a file, such as the AmplifierS2D. No DAC is needed.
• You have a dataset or data file, but the component you want to use doesn't read the data directly. Use a DataAccessComponent to link the data file and component. The component you choose must have the file-based option under the Parameter Entry Mode or the parameter AllParams. For example, the BJTM1 model has the parameter AllParams; the R component has the Parameter Entry Mode. For instructions on how to use a DAC, see DataAccessComponent (Data Access Component) or Schematic Capture and Layout.

Reading and Writing Data Files

Use the Data File Tool to import and export data between datasets and text files that are in the following file formats:

• Touchstone
• Measurement data interchange format (MDIF)
• CITIfile
• IC-CAP

You can transfer data from a file into a dataset, or vice versa. One application is to transfer data from a dataset to an MDIF file, for use with a specific type of component. For example, a file in P2D format (P2D is one of several MDIF formats) containing S-parameters can then be used by the P2D amplifier. Using the Data File Tool, you can write S-parameters from a dataset to a file in P2D format. Another application is reading Agilent IC-CAP data into a dataset to be used in conjunction with a component, such as a source, that can read data from a dataset.

See the table above in Supported Data Formats for a list of the available file types, a description of the file contents, and the component that uses the data. Be sure to review the notes at the end of the table. The details about each file format are described later in this topic.

Starting and Exiting the Data File Tool

You can start the Data File Tool from a Schematic window or a Data Display Window.

• From a Schematic window, choose Tools > Data File Tool. Or, click the Data File Tool icon.
  
• From a Data Display window, choose Tools > Data File Tool. Or, click the Data File Tool icon.
  

To exit the Data File Tool, choose File > Exit from the menu bar.

Parts of the Data File Tool

The following illustration shows the default appearance of the Data File Tool user interface for a UNIX-based system when the Data File Tool is started.

The layout of the interface and names of the various elements vary with the task being performed (read or write) and can also vary with the file format selected. Examples of this variation in the appearance of the Data File Tool user interface is shown in the two following figures.

Data File Tool in read mode

Data File Tool in write mode

These are the more frequently used elements of the interface:

• The Menu bar displays the menus that are available in the Data File Tool window.
• The Dataset field lists the datasets in the current project. The selected dataset or the name of a new dataset is displayed in the Dataset name field.

Reading a File

To read the contents of a file into a dataset:

1. From an open Data File Tool window, click Read data file into dataset.
2. Under File format to read, select one of the following file formats:
   • Touchstone
   • MDIF
   • Citifile
   • ICCAP
3. For the MDIF format, choose the appropriate sub-format from MDIF sub type.
4. Under Input file name, type in the file name if the file is in the project. If it is not, click Browse to locate and select the file.
5. The data from the selected file will be written to a dataset. Enter a name in the Dataset name field or select from the existing datasets in the Datasets list. If you choose a dataset from the list, any data that is already stored in the dataset will not be saved and will be overwritten with new data.
6. Click Read File to send the file contents to the dataset.

   Note The source file must not use any ADS reserved variables or non-ASCII characters. Use of such a file can produce misleading results.

Writing to a File

To write data to a file:

1. From an open Data File Tool window, click Write data file from dataset.
2. Under File format to write, select one of the following file formats:
   • Touchstone
   • MDIF
   • Citifile
3. For the Touchstone and MDIF formats, choose the appropriate sub-format from Touchstone data type, or MDIF sub type.
4. Under Output file name, type in the file name you want to write to. It will be saved in the project directory. If you want to save the file in a different location, click Browse to select a location.
5. Under Complex data format, select the complex data format to be used in the file.
6. For Touchstone and MDIF files, under Frequency units, select the frequency units to be used in the file.
7. Under Data notation format, select the data notation format to be used in the file.
8. Under Max resolution, select the maximum resolution to be used in the file.
9. The source of the data can be any project dataset. It should contain data matching the file format selected. Select an existing dataset from the Datasets list. Click View Dataset to view the contents of the selected dataset.
10. Click Write to File to send the data to the file.

    Note If a dataset has just been created by reading a file, it might be necessary to click Update Dataset List to see it appear in the list.

Examples

You can find designs that use different data files in the Examples directory under Data_comp_prj and DataAccess_prj.

Instructions for using a particular type of file with a component that is designed to read the file (like an . snp file and SnP component) can be found in the remaining reference sections.

Touchstone SnP Format

These files contain small-signal G-, H-, S-, Y-, or Z-network parameters described by frequency-dependent linear network parameters for 1- to 99-port components. The 2-port component files can also contain frequency-dependent noise parameters. This data file format is also known as Touchstone format.

An .snp file can be used with an SnP component to model the behavior of a linear model using S-parameters. The file contains the S-parameters, the component is placed within the schematic.

This section describes:

• Choosing an .snp file for use with an SnP component
• An overview of the SnP file
• The basic SnP format
• Adding noise to a 2-port Snp file
• The basic SnP format applied to G-, H-, S-, Y-, and Z-parameters, plus examples of each

Linking an .snp File to an SnP Component

To link a file to the component:

1. Add an SnP component to your schematic. It can be found in the Data Items library.
2. Select the File parameter. Ensure that the Parameter Entry Mode is set to Network Parameter File Name .
3. In the File Name field, enter the name of the file you want to use:
   • You can type the name directly in the field.
   • Click Data files list to locate a file in the current project (or any files located based on the setting of the DATAFILES variable in de_sim.cfg).
   • Click Browse to locate a file outside the current project.
   • Click Copy template to select an example file that you can customize.
4. After you select a file, click Edit if you want to view the file or change its contents.

For instructions on how to set the remaining parameters, click Help in the open component dialog box.

Overview

SnP data files are ASCII text files in which data appears line by line, one line per data point, in increasing order of frequency. Each line of data consists of a frequency value and one or more pairs of values for the magnitude and phase of each S-parameter at that frequency. Values are separated by one or more spaces, tabs or commands. Comments are preceded by an exclamation mark (!). Comments can appear on separate lines, or after the data on any line or lines. Extra spaces are ignored. Recommendations for filenames are:

1-port: filename.s1p

2-port: filename.s2p

Up to 99 ports can be defined.

You can specify the following parameters in an .snp file:

Note The mismatched port impedance is not supported by the ADS simulator. If a Touchstone file has the input/output mismatch information in the header, it is ignored by the DAC and the SnP components, and a default matching 50 ohm port impedance is used.

Basic SnP File Format

The following example shows the general format for component data files. It consists of:

• An option line
• Data lines
• Comments

The Option Line

The option line, specifying the frequency units and the normalizing impedance, precedes the data lines.
# (freq_units parameter format R n)
<data line>
...
<data line>
where:

In summary, the option line should read:

where square brackets [...] indicate optional information; .../.../.../ indicates that you select one of the choices; and, n is replaced by a positive number.

Default Option Line

The default option line for component data files is:
# GHZ S MA R 50

Option Line Examples

Frequency in GHz, S-parameters in real-imaginary format, normalized 100 ohms:
# GHz S RI R 100
Frequency in KHz, Y-parameters in real-imaginary format, normalized 100 ohms:
# KHz Y RI R 100
Frequency in Hz, Z-parameters in magnitude-degree format, normalized to 1 ohm:
# Hz Z MA R 1
Frequency in KHz, H-parameters in real-imaginary format normalized to 1 ohm:
# KHz H RI R 1
Frequency in Hz, G-parameters in magnitude-degree, format normalized to 1 ohm:
# Hz G MA R 1

Data Lines

Data lines contain the data of interest. A special format is used for 2-port data files where all of the network parameter data for a single frequency is listed on one line. The order of the network parameters is:

N11, N21, N12, N22

For 3-port or higher data files, the network parameters appear in the file in a matrix form, each row starting on a separate line. A maximum of four network parameters (with 2 real numbers for each) appear on any line. The remaining network parameters are continued on as many additional lines as are needed.

The following sections describe the data-line format for single and multi-port components.

Data-line Formats

When you type the data below the option line, the columns need not line up precisely like those shown. The syntax for entering data is as follows:

1-port Component
Magnitude-Angle format:

2-port Component
Magnitude-Angle format:

Real-Imaginary format:

where

3-port Component
Magnitude-Angle format:

4-port Component
Magnitude-Angle format:

where:

Adding Comments to Data Files

You can document your data files by preceding a comment with the exclamation mark (!) on any line. A comment can be the only entry on a line or can follow the data on any line.

Adding Noise Parameters to an SnP File

Noise parameters can be included in SnP 2-port data files. Noise data can follow G-, H-, S-, Y-, or Z-parameters described for each frequency. The x values are data.

Each line of a noise parameter has the following five entries:

x1 x2 x3 x4 x5

where:

Sopt noise data in an SnP file must be expressed in a Magnitude/Angle (MA) format. The simulator assumes that the Sopt noise data in an SnP file is specified in a MA format. This is the only supported format for Sopt data in an SnP file. The complex format type specified in the format line does not apply to the Sopt data specified in the Noise block.

The data file reader cannot determine if the numbers representing the Sopt data in the SnP data file are expressed in MA format and not in dB or Real/Imag formats. It reads in whatever numbers appear on the data line and processes them as if they are MA, without issuing an error or warning message. If the Sopt data in the SnP data file is expressed in a format other than MA, this can produce simulation data that look incorrect.

Note The frequencies for noise parameters and network parameters need not match. The only requirement is that the lowest noise-parameter frequency be less than or equal to the highest network-parameter frequency. This allows the file processor to determine where network parameters end and noise parameters begin.

The source reflection coefficient and effective noise resistance are normalized to the same resistance as specified for the network parameters.

Example File Containing Noise Data

This is an example of a data file with noise data:

! NEC710
# GHZ S MA R 50
 2    .95    -26    3.57    157    .04    76    .66    -14
22    .60    -144   1.30     40    .14    40    .56    -85
! NOISE PARAMETERS
 4    .7      .64     69    .38
18     2.7    .46    -33    .40

Applying the SnP Format, and Examples

In this section are formatting references and examples for:

• G-parameter files
• H-parameter files
• S-parameter files
• Y- and Z-parameter files

Guidelines

• The optimum source reflection coefficient and the normalized effective noise resistance are assumed to be with respect to the normalizing resistance value (appearing after the R keyword) on the header line.
• The frequencies for noise parameters and G-, H-, S-, Y-, or Z-parameters (network parameters) do not have to match. The only requirement is that the lowest noise parameter frequency be less than or equal to the highest network parameter frequency. This allows the file processor to determine where G-, H-, S-, Y-, or Z-parameters end and noise parameters begin.

G-Parameter Files

G-parameter files (Hybrid-g parameters) use MA or RI format. They are strictly 2-port files. G-parameter measurements are:

G-Parameter MA and RI File Formats

#    frequency_unit    G    MA    R    impedance
freq  magG11  angG11  magG21  angG21  magG12  angG12  magG22  angG22
#    frequency_unit    G    RI    R    impedance
freq  reG11   imG11   reG21   imG21   reG12    mG12   reG22   imG22

G-Parameter File Example

! symbol freq-unit parameter-type data-format keyword impedance-ohms
#      KHZ      G      MA      R      1
! freq  magG11  angG11  magG21  angG21  magG12  angG12  magG22  angG22
  2    .95     -26      3.57    157    .04      76     .66     -14
  3    .93     -40      3.53    147    .05      69     .65     -20
  4    .89     -52      3.23    136    .06      62     .63     -26

H-Parameter Files

H-parameter files (Hybrid-h parameters) use MA or RI format. They are strictly 2-port files. H-parameter measurements are:

H-Parameter File Example

! symbol  freq-unit  parameter-type  data-format  keyword  impedance-ohms
#   KHZ      H       MA      R      1
! freq  magH11  angH11  magH21  angH21  magH12  angH12  magH22  angH22
  2     .95     -26     3.57    157     .04     76      .66     -14
  3     .93     -40     3.53    147     .05     69      .65     -20
  4     .89     -52     3.23    136     .06     62      .63     -26

S-Parameter Files

S-parameter files (scattering parameters) can have MA, RI, or DB format for files with 1 to 99 ports.

S-Parameter 1-Port MA, RI, and DB File Formats

#      frequency_unit      S      MA      R      impedance
freq      magS11      angS11
#      frequency_unit      S      RI      R      impedance
freq      reS11      imS11
#      frequency_unit      S      DB      R      impedance
freq      dbS11      angS11

S-Parameter 2-Port MA, RI, and DB File Formats

#   frequency_unit   S   MA   R   impedance
freq  magS11  angS11  magS21  angS21  magS12  angS12  magS22  angS22
#   frequency_unit   S   RI   R   impedance
freq  reS11   imS11   reS21   imS21   reS12   imS12   reS22   imS22
#   frequency_unit   S   DB   R   impedance
freq  dbS11   angS11   dbS21  angS21  dbS12   angS12  dbS22   angS22

S-Parameter 3-Port MA, RI, and DB File Formats

#   frequency_unit   S   MA   R   impedance
freq   magS11  angS11  magS12  angS12  magS13  angS13 ! 1st row
       magS21  angS21  magS22  angS22  magS23  angS23 ! 2nd row
       magS31  angS31  magS32  angS32  magS33  angS33 ! 3rd row
#      frequency_unit      S      RI      R      impedance
freq   reS11   imS11   reS12   imS12   reS13   imS13 ! 1st row
       reS21   imS21   reS22   imS22   reS23   imS23 ! 2nd row
       reS31   imS31   reS32   imS32   reS33   imS33 ! 3rd row
#   frequency_unit   S   DB   R   impedance
freq   dbS11   angS11  dbS12   angS12  dbS13   angS13 ! 1st row
       dbS21   angS21  dbS22   angS22  dbS23   angS23 ! 2nd row
       dbS31   angS31  dbS32   angS32  dbS33   angS33 ! 3rd row

S-Parameter 4-Port MA, RI, and DB File Formats

#   frequency_unit      S      MA      R      impedance
! 1st row
freq  magS11  angS11  magS12  angS12  magS13  angS13  magS14  angS14
      magS21  angS21  magS22  angS22  magS23  angS23  magS24  angS24 ! 2nd row
      magS31  angS31  magS32  angS32  magS33  angS33  magS34  angS34 ! 3rd row
      magS41  angS41  magS42  angS42  magS43  angS43  magS44  angS44 ! 4th row
#   frequency_unit      S      RI      R      impedance
freq  reS11   imS11   reS12   imS12   reS13   imS13   reS14   imS14 ! 1st row
      reS21   imS21   reS22   imS22   reS23   imS23   reS24   imS24 ! 2nd row
      reS31   imS31   reS32   imS32   reS33   imS33   reS34   imS34 ! 3rd row
      reS41   imS41   reS42   imS42   reS43   imS43   reS44   imS44 ! 4th row
#   frequency_unit      S      DB      R      impedance
freq  dbS11   angS11  dbS12   angS12  dbS13   angS13  dbS14   angS14 ! 1st row
      dbS21   angS21  dbS22   angS22  dbS23   angS23  dbS24   angS24 ! 2nd row
      dbS31   angS31  dbS32   angS32  dbS33   angS33  dbS34   angS34 ! 3rd row
      dbS41   angS41  dbS42   angS42  dbS43   angS43  dbS44   angS44 ! 4th row

S-Parameter 1-Port File Example

! symbol  freq-unit  parameter-type  data-format  keyword  impedance-ohms
#    MHZ   S    MA    R     50
! freq  magS11  angS11  (commented header line)
    2.000    0.894    -12.136
    3.000    0.893    -18.179
    4.000    0.891    -24.193

S-Parameter 5- to 99-Port File Formats

These file formats appear in a matrix form similar to the 3- and 4-port files, except that only four S-parameters (with 2 real numbers for each) can appear on a given line. Therefore, the remaining S-parameters in that row of the S-matrix continue on the next line of the file.

Each row of the S-matrix must begin on a new line of the file. The first line of the first row of the S-matrix begins with the frequency value.

S-Parameter 10-Port File Example (at One Frequency)

#      frequency_unit      S      MA      R      impedance
freq magS11 angS11 magS12 angS12 magS13 angS13 magS14 angS14 ! 1st row
magS15 angS15 magS16 angS16 magS17 angS17 magS18 angS18
magS19 angS19 magS1,10 angS1,10
magS21 angS21 magS22 angS22 magS23 angS23 magS24 angS24 ! 2nd row
magS25 angS25 magS26 angS26 magS27 angS27 magS28 angS28
magS29 angS29 magS2,10 angS2,10
magS31 angS31 magS32 angS32 magS33 angS33 magS34 angS34 ! 3rd row
magS35 angS35 magS36 angS36 magS37 angS37 magS38 angS38
magS39 angS39 magS3,10 angS3,10
magS41 angS41 magS42 angS42 magS43 angS43 magS44 angS44 ! 4th row
magS45 angS45 magS46 angS46 magS47 angS47 magS48 angS48
magS49 angS49 magS4,10 angS4,10
magS51 angS51 magS52 angS52 magS53 angS53 magS54 angS54 ! 5th row
magS55 angS55 magS56 angS56 magS57 angS57 magS58 angS58
magS59 angS59 magS5,10 angS5,10
magS61 angS61 magS62 angS62 magS63 angS63 magS64 angS64 ! 6th row
magS65 angS65 magS66 angS66 magS67 angS67 magS68 angS68
magS69 angS69 magS6,10 angS6,10
magS71 angS71 magS72 angS72 magS73 angS73 magS74 angS74 ! 7th row
magS75 angS75 magS76 angS76 magS77 angS77 magS78 angS78
magS79 angS79 magS7,10 angS7,10
magS81 angS81 magS82 angS82 magS83 angS83 magS84 angS84 ! 8th row
magS85 angS85 magS86 angS86 magS87 angS87 magS88 angS88
magS89 angS89 magS8,10 angS8,10
magS91 angS91 magS92 angS92 magS93 angS93 magS94 angS94 ! 9th row
magS95 angS95 magS96 angS96 magS97 angS97 magS98 angS98
magS99 angS99 magS9,10 angS9,10
!10th row
magS10,1 angS10,1 magS10,2 angS10,2 magS10,3 angS10,3 magS10,4 angS10,4
magS10,5 angS10,5 magS10,6 angS10,6 magS10,7 angS10,7 magS10,8 angS10,8
magS10,9 angS10,9 magS10,10 angS10,10

Linear 1-Port (.s1p) File Example

# GHZ      S      RI      R      50.0
        1.00000000        0.9488        -0.2017
        1.50000000        0.9077        -0.3125
        2.00000000        0.8539        -0.4165
        2.50000000        0.7884        -0.5120
        3.00000000        0.7124        -0.5978
        3.50000000        0.6321        -0.6546
        4.00000000        0.5479        -0.7013
        4.50000000        0.4701        -0.7380
        5.00000000        0.3904        -0.7663
        5.50000000        0.3302        -0.7778
        6.00000000        0.2702        -0.7848
        6.50000000        0.2041        -0.7890
        7.00000000        0.1389        -0.7878
        7.50000000        0.0894        -0.7849
        8.00000000        0.0408        -0.7789
        8.50000000        0.0134        -0.7649
        9.50000000        0.0654        -0.7471
        9.00000000        0.1094        -0.7319
        10.0000000        0.1518        -0.7140

Linear 2-Port (.s2p) File Example

# GHZ       S      RI      R      50.0
1.0000 0.3926 -0.1211 -0.0003 -0.0021 -0.0003 -0.0021 0.3926 -0.1211
2.0000 0.3517 -0.3054 -0.0096 -0.0298 -0.0096 -0.0298 0.3517 -0.3054
10.000 0.3419  0.3336 -0.0134  0.0379 -0.0134  0.0379 0.3419  0.3336
!Noise params
 1.0000    2.0000    -0.1211    -0.0003    .4
 2.0000    2.5000    -0.3054    -0.0096    .45
 3.0000    3.0000    -0.6916    -0.6933    .5
 4.0000    3.5000    -0.3756     0.4617    .55
 5.0000    4.0000     0.3880     0.6848    .6
 6.0000    4.5000     0.0343     0.0383    .65
 7.0000    5.0000     0.6916     0.6933    .7
 8.0000    5.5000     0.5659     0.1000    .75
 9.0000    6.0000     0.4145     0.0307    .8
10.0000    6.5000     0.3336     0.0134    .85

Linear 3-Port (.s3p) File Example

#  GHZ    S    MA    R    50.0
!  POWER DIVIDER, 3-PORT
5.00000  0.24254  136.711  0.68599  -43.3139  0.68599 -43.3139
         0.68599 -43.3139  0.08081   66.1846  0.28009 -59.1165
         0.68599 -43.3139  0.28009  -59.1165  0.08081  66.1846
6.00000  0.20347  127.652  0.69232  -52.3816  0.69232 -52.3816
         0.69232 -52.3816  0.05057   52.0604  0.22159 -65.1817
         0.69232 -52.3816  0.22159  -65.1817  0.05057  52.0604
7.00000  0.15848  118.436  0.69817  -61.6117  0.69817 -61.6117
         0.69817 -61.6117  0.02804   38.6500  0.16581 -71.2358
         0.69817 -61.6117  0.16581  -71.2358  0.02804  38.6500

Linear 4-Port (.s4p) File Example

#  GHZ    S    MA    R    50

5.00000 0.60262  161.240  0.40611 -42.2029 0.42918 -66.5876  0.53640 -79.3473
        0.40611 -42.2029  0.60262  161.240 0.53640 -79.3473  0.42918 -66.5876
        0.42918 -66.5876  0.53640 -79.3473 0.60262  161.240  0.40611 -42.2029
        0.53640 -79.3473  0.42918 -66.5876 0.40611 -42.2029  0.60262  161.240
6.00000 0.57701  150.379  0.40942 -44.3428 0.41011 -81.2449  0.57554 -95.7731
        0.40942 -44.3428  0.57701  150.379 0.57554 -95.7731  0.41011 -81.2449
        0.41011 -81.2449  0.57554 -95.7731 0.57701  150.379  0.40942 -44.3428
        0.57554 -95.7731  0.41011 -81.2449 0.40942 -44.3428  0.57701  150.379
7.00000 0.50641  136.693  0.45378 -46.4151 0.37845 -99.0918  0.62802 -114.196
        0.45378 -46.4151  0.50641  136.693 0.62802 -114.196  0.37845 -99.0918
        0.37845 -99.0918  0.62802 -114.196 0.50641  136.693  0.45378 -46.4151
        0.62802 -114.196  0.37845 -99.0918 0.45378 -46.4151  0.50641  136.693

Y- and Z-Parameter Files

Immittance parameters are specified in MA or RI format, where the # line has Y for admittance and Z for impedance. Both are normalized to the reference resistance.

Y- (Z-) Parameter 1-Port MA and RI File Formats

#   frequency_unit    Y    MA    R    impedance
freq   magY11  angY11
#   frequency_unit    Y    RI    R    impedance
freq   reY11   imY11

Y- (Z-) Parameter 2-Port MA and RI File Formats

#    frequency_unit    Y    MA    R    impedance
freq  magY11  angY11  magY21  angY21  magY12  angY12  magY22  angY22
#    frequency_unit    Y    RI    R    impedance
freq  reY11   imY11   reY21   imY21   reY12   imY12   reY22   imY22

Y- (Z-) Parameter 3-Port MA and RI File Formats

freq   magY11 angY11 magY12 angY12 magY13 angY13 ! 1st row
       magY21 angY21 magY22 angY22 magY23 angY23 ! 2nd row
       magY31 angY31 magY32 angY32 magY33 angY33 ! 3rd row
#    frequency_unit    Y    RI    R    impedance
freq   reY11  imY11  reY12  imY12  reY13  imY13 ! 1st row
       reY21  imY21  reY22  imY22  reY23  imY23 ! 2nd row
       reY31  imY31  reY32  imY32  reY33  imY33 ! 3rd row

Y- (Z-) Parameter 4-Port MA and RI File Formats

#  frequency_unit  Y  MA  R  impedance
freq magY11 angY11 magY12 angY12 magY13 angY13 magY14 angY14 ! 1st row
     magY21 angY21 magY22 angY22 magY23 angY23 magY24 angY24 ! 2nd row
     magY31 angY31 magY32 angY32 magY33 angY33 magY34 angY34 ! 3rd row
     magY41 angY41 magY42 angY42 magY43 angY43 magY44 angY44 ! 4th row
#  frequency_unit  Y  RI  R  impedance
freq reY11 imY11 reY12 imY12 reY13 imY13 reY14 imY14 ! 1st row
     reY21 imY21 reY22 imY22 reY23 imY23 reY24 imY24 ! 2nd row
     reY31 imY31 reY32 imY32 reY33 imY33 reY34 imY34 ! 3rd row
     reY41 imY41 reY42 imY42 reY43 imY43 reY44 imY44 ! 4th row

Y- (Z-) Parameter 3-Port File Example

! symbol freq-unit parameter-type data-format keyword impedance-ohms
      #    GHz       Y             MA           R       1
!freq magY11  angY11 magY12   angY12 magY13   angY13 ! 1st line
!     magY21  angY21 magY22   angY22 magY23   angY23 ! 2nd line
!     magY31  angY31 magY32   angY32 magY33   angY33 ! 3rd line
  4    0.008  83.122 8.5e-04 -86.740  0.007  -98.037
       0.046 -12.740 0.005    36.580  0.049  171.554
       0.046 177.588 0.004  -152.638  0.050    0.134
  8    0.016  79.068 0.002   -84.015  0.014 -102.924
       0.049 -23.015 0.006    52.828  0.051  164.123
       0.048 175.827 0.005  -139.640  0.052   -0.004
 12    0.025  73.501 0.003   -81.736  0.023 -109.374
       0.058 -36.736 0.009    58.596  0.058  152.007
       0.055 169.129 0.007  -136.047  0.059   -5.349
 18    0.036  65.138 0.004   -71.761  0.033 -119.900
       0.059 -54.761 0.013    72.274  0.052  137.118
       0.052 162.979 0.010  -121.976  0.055   -6.677

Y- (Z-) Parameter 5- to 99-Port File Formats

These file formats appear in a matrix form similar to 3- and 4-port files. Only four Y-, or Z-parameters (with 2 real numbers for each) can appear on a given line; therefore, the remaining parameters in that row of the matrix continue on the next line of the file. Each row of the Y-matrix must begin on a new line of the file. The first line of the first row of the Y-matrix begins with the frequency value. The actual Y- (Z-) parameter value is obtained by dividing (multiplying) the file entry with the reference resistance.

Y- (Z-) Parameter 10-Port File Example (at One Frequency)

#  frequency_unit   Y   MA   R   impedance
freq magY11 angY11 magY12 angY12 magY13 angY13 magY14 angY14 ! 1st row
magY15 angY15 magY16 angY16 magY17 angY17 magY18 angY18
magY19 angY19 magY1,10 ngY1,10
magY21 angY21 magY22 angY22 magY23 angY23 magY24 angY24 ! 2nd row
magY25 angY25 magY26 angY26 magY27 angY27 magY28 angY28
magY29 angY29 magY2,10 angY2,10
magY31 angY31 magY32 angY32 magY33 angY33 magY34 angY34 ! 3rd row
magY35 angY35 magY36 angY36 magY37 angY37 magY38 angY38
magY39 angY39 magY3,10 angY3,10
magY41 angY41 magY42 angY42 magY43 angY43 magY44 angY44 ! 4th row
magY45 angY45 magY46 angY46 magY47 angY47 magY48 angY48
magY49 angY49 magY4,10 angY4,10
magY51 angY51 magY52 angY52 magY53 angY53 magY54 angY54 ! 5th row
magY55 angY55 magY56 angY56 magY57 angY57 magY58 angY58
magY59 angY59 magY5,10 angY5,10
magY61 angY61 magY62 angY62 magY63 angY63 magY64 angY64 ! 6th row
magY65 angY65 magY66 angY66 magY67 angY67 magY68 angY68
magY69 angY69 magY6,10 angY6,10
magY71 angY71 magY72 angY72 magY73 angY73 magY74 angY74 ! 7th row
magY75 angY75 magY76 angY76 magY77 angY77 magY78 angY78
magY79 angY79 magY7,10 angY7,10
magY81 angY81 magY82 angY82 magY83 angY83 magY84 angY84 ! 8th row
magY85 angY85 magY86 angY86 magY87 angY87 magY88 angY88
magY89 angY89 magY8,10 angY8,10
magY91 angY91 magY92 angY92 magY93 angY93 magY94 angY94 ! 9th row
magY95 angY95 magY96 angY96 magY97 angY97 magY98 angY98
magY99 angY99 magY9,10 angY9,10
!10th row
magY10,1 angY10,1 magY10,2 angY10,2 magY10,3 angY10,3 magY10,4 angY10,4
magY10,5 angY10,5 magY10,6 angY10,6 magY10,7 angY10,7 magY10,8 angY10,8
magY10,9 angY10,9 magY10,10 angY10,10

ADS Impulse File Format

ADS Impulse ( .imp ) files store multi-port impulse responses of linear N-ports. For a frequency domain N-port description:

,

.imp files provide a method of storing the time domain equivalent of,

,

where h_ij(t) is the impulse response of matrix element H_ij(ω).

ADS impulse files store discrete, uniformly sampled representations Imp_ij(n) of impulse responses h_ij(t) normalized by the sampling step, and optionally allow for explicit storage of the impulse response delay, as illustrated in the following figure:

More specifically,

Imp_ij(n)=h_ij(T_d+nΔT)ΔT ,

where T_d is the base delay and ΔT is the sample spacing.

.imp files are the time-domain analog of the frequency-domain Touchstone format. They consist of comments, header lines and data lines, similar to Touchstone. Header lines describe global settings while data lines describe impulse response matrices, as detailed below.

Comments

Comments are preceded by an exclamation mark (!). Comments may be placed at the beginning or at the end of a line.

Line Continuation

Carriage return is used as the line continuation character.

Header Lines

Header lines consist of the Option line and the following keywords:

• [Version]
• [Number of Ports]
• [Reference]
• [Original Frequency Range]
• [Time Step]
• [Base Delay]

With the exception of the Option line, all keywords are enclosed in the square brackets. Header lines, including keywords and the Option line, may appear in any order. Header lines precede data lines and may not appear after the data section.

The Option Line

The Option line specifies the network parameter type and the normalizing impedance. The Option line format is:

# parameter R n

where:

Option Line Examples

S-parameters impulse response, normalized to 100Ω:

# S R 100.0

Y-parameter impulse response:

# Y

Z-parameter impulse response:

# Z

[Version]

The [Version] keyword defines the version of the .imp file. The [Version] line is of the form:

[Version] version

The initial version is 1.0. [Version] is optional and defaults to 1.0.

[Version] Line Example

[Version] 1.0

[Number of Ports]

The [Number of Ports] keyword defines the number of network ports. The [Number of Ports] line is of the form

[Number of Ports] n

[Number of Ports] is mandatory.

[Number of Ports] Line Example

[Number of Ports] 2

[Reference]

The [Reference] keyword defines the port reference impedances for impulse data in S-parameter form. The [Reference] line is of the form:

[Reference] ref1 ref2 ... refN

where ref1, ref2 ... refN define the reference impedance for each port.

This keyword is optional. If [Reference] is not present, the reference impedances are defined by the Option line. If [Reference] is present, it must contain an entry for every port (for example, a four-port data file using [Reference] must contain four [Reference] impedance entries). If reference impedances are specified both using [Reference] and in the Option line, the [Reference] line takes precedence.

[Reference] Line Example

A two-port network with port 1 terminated into 75Ω and port 2 terminated into 75Ω:

[Reference] 75.0 75.0

[Original Frequency Range]

This keyword defines the frequency range of the frequency domain network parameters from which the .imp file was extracted. [Original Frequency Range] is optional. The line is of the form:

[Original Frequency Range] minFreq maxFreq units

where

[Original Frequency Range] Line Example

[Original Frequency Range] 0.05 20.0 GHz

[Time Step]

The [Time Step] keyword defines the uniform sampling step for the impulse response. This line is of the form:

[Time Step] timeStep units

where

The [Time Step] line is mandatory.

[Time Step] Line Example

[Time Step] 1.0 nsec

[Base Delay]

The [Base Delay] keyword defines the base delay of each impulse response. [Base Delay] is of the form:

[Base Delay] baseDelay1 baseDelay2 ... baseDelayM units

where

[Base Delay] Line Example

If the impulse response matrix has the following hypothetical base delays:

Base delay (1,1) = 1.0 nsec
Base delay (1,2) = 2.0 nsec
Base delay (2,1) = 3.0 nsec
Base delay (2,2) = 4.0 nsec,

it would be expressed by the [Base Delay] line as follows:

[Base Delay] 1.0 2.0 3.0 4.0 nsec

Data Lines

Data lines define the impulse response matrix. Data lines follow Header lines. Data lines are of the form:

[Number of Points] P11
sample1 sample2 ... sampleP11

[Number of Points] P12
sample1 sample2 ... sampleP12

...

[Number of Points] PNN
sample1 sample2 ... samplePNN

where

There are N² data lines for an N-port network. Impulse responses are ordered row-wise.

Data Lines Example

[Number of time points] 4
3.409677e-01 2.650540e-01 1.488737e-01 0.0

[Number of time points] 6
3.288703e-02 -8.949016e-03 -7.373915e-04 3.288703e-02 -8.949016e-03 0.0

[Number of time points] 6
3.288703e-02 -8.949016e-03 -7.373915e-04 3.288703e-02 -8.949016e-03 0.0

[Number of time points] 4
3.409677e-01 2.650540e-01 1.488737e-01 0.0

Example .imp File

!2-port S-parameter file
[Version] 1.0
# S R 5.000000e+01
[Number of Ports] 2
[Reference] 75.0 75.0 
[Original Frequency Range] 0.000000e+00 1.000000e+10 Hz
[Time Step] 2.500000e-11 sec
[Base Delay] 0.000000e+00 1.731859e-09 
1.731859e-09 0.000000e+00 

[Number of time points] 4 		!S11
3.409677e-01 2.650540e-01 1.488737e-01 0.0
[Number of time points] 6		!S12
3.288703e-02 -8.949016e-03 -7.373915e-04 3.288703e-02 -8.949016e-03 0.0
[Number of time points] 6		!S21
3.288703e-02 -8.949016e-03 -7.373915e-04 3.288703e-02 -8.949016e-03 0.0
[Number of time points] 4		!S22
3.409677e-01 2.650540e-01 1.488737e-01 0.0

Discrete Format

The discrete data file consists of an array of data arranged in rows and columns. The values available for each parameter are arranged in columns. Following the BEGIN DSCRDATA line is the % format line which specifies the names of dependent variables. The first column is always treated as a string; other columns are real, integer or string, depending on the first row of data.

The first column, under the heading Index in the example below, contains entries used to identify each row in the file. These entries can be either an integer or an alphanumeric identifier, and can be thought of as a list of specification numbers (or part numbers). For example, the data file data/stdvalues15.dscr is arranged as follows:

REM     stdvalues15.dscr
BEGIN DSCRDATA
%  INDEX      A12      A13
     1        1000      1000
     2        1000      1200
     3        1000      2200
     4        1200      1000
     5        1200      1200
     6        1200      2200
END DSCRDATA

Selecting a Row

A row of data can be selected by specifying its row index (starting from 0). In this example, the file lists two columns of values labeled A12 and A13. By specifying 2 as the row number, the values 1000 and 2200 are selected for A12 and A13, respectively.

Using the File with a DAC

To use the data within the file, you must link the file to the component of interest. You reference a discrete data file in this way by using a DAC:

1. Place a DataAccessComponent data item in your design. The DAC is located in the Data Items palette. Double-click the DAC to edit it.
2. On the File tab, in the File Name field, specify the name of the discrete data file, and accept the default setting for File Type , which is Discrete .
3. On the Interpolation tab, accept the defaults for Interpolation Method ( Index Lookup ) and for Interpolation Domain ( Rectangular ).
4. On the Independent Variable tab, set the names and values for the independent variables. This is necessary since data in a discrete data file can be accessed only by using an index lookup value. This means looking up data by row number.
   To set up an independent variable, enter the name in the Variable Name field. For a discrete data file, the innermost independent variable is the dimension number which should be used as the name. Next, enter the row number in the Value field, which can be a variable assigned a value on the schematic. Then click Add to insert the name and value in the table at the left. Repeat this process for each independent variable in the data file.
   Values entered for Variable Name are treated as strings, and quotation marks are inserted with these values automatically when added to the table's Name column. However, the innermost independent variable of a discrete data file must be specified as a cardinal integer instead of a string name. Assuming you are working with a one-dimensional data file, enter @1 to enter the integer (@ suppresses the quotation marks). For example, here is a portion of a one-dimensional discrete data file:

   Begin dscrdata
   % index mydata
   0 12
   1 34
   2 56
   .....
   end

   If you define a variable called MyIndex in a schematic whose value represents the index of the row of data to be accessed, the table of independent variables should be constructed this way to read the one-dimensional file:

   Name Value
   1 MyIndex

   The value assigned to MyIndex in the schematic determines which row of data is read. So if MyIndex = 0 , the first row is read.

5. Place the component whose parameter values should come from the data file. Double-click the component.
6. Under Pa rameter Entry Mode, select File Based.
7. Under Data Access Component Instance , enter the ID of the desired DAC data item.
8. Under Dependent Parameter Name , enter the name of a dependent variable in the discrete data file (In the sample above, the dependent variable names are A12 and A13.).

Example

For an example of using a discrete data file, refer to amp1.dsn in the Examples directory, under Tutorials/DataAccess_prj .

Model MDIF Files

Nonlinear devices obtain their model parameters either from a model item or a file. For those devices that use a file, such as the EE_BJT2_Model , this section discusses the appropriate format for a model file, and how to read the file.

Model files are text files that contain model parameter names and values. A sample model file for the EE_BJT2_Model is shown below. Comments can be placed in the file by starting the line with REM . The model parameters are placed between BEGIN BDTA and END BDTA . One or more parameter names are placed on a line beginning with the percent symbol (%); corresponding values are placed in the same order on the next line. Parameter names can be in any order and are not case sensitive. Any parameters that are not present in the file take on their documented default values. Parameter names for each device are listed in the documentation for that device.

REM any line that starts with REM is ignored
BEGIN BDTA
% Rb          Rc       Re          Tamb     Ibir        Nbr
  0.637326    5.17646  0.695       25       3.72528e-15 1.0537
% Isc         Nc       Ibif        Nbf      Ise         Ne
  0           2        5.70565e-17 1.10843  4.63077e-14 1.83578
% Var         Nr       Isr         Ikr      Vaf         Nf
  1.1858      1.02201  1.12936e-14 100      54.9731     0.977768
% Isf         Ikf      Cjc         Vjc      Mjc         Cje
  5.37696e-16 0.857731 5.87976e-13 0.313492 0.0650757   9.81026e-13
% Vje         Mje      Tf          Tr       Fc
  1.05535     0.475724 2.09636e-12 0        0.9
% Xtf         Vtf      Itf
  10          4.32912  1e-09
END BDTA

The following figure shows how to obtain parameter values from a model MDIF file using a DataAccessComponent. The DAC refers to the model file by name. In this example, the file name is bfqtm1.txt . Additionally, Type is set to MDIFmodel and ExtrapMode set to InterpolationMode . On the device model component, the AllParams parameter is set to the name of the DAC, which is DAC_BJT .

Reading a Model MDIF file using a DataAccessComponent

PDF Format

This format is for user-specified Probability Density Functions (PDF). PDF is used for arbitrary distributions that are not correlated. The two methods available accommodate:

• Situations where the spread of statistical data is proportional to the nominal value (as in a percent tolerance).
• Situations where the spread is independent of the nominal value (an absolute tolerance).

Probability density functions are represented as vertices of piecewise linear segments. These value/ordinate pairs are stored in a textual data file in a prescribed format. The nominal value is also stored.

User-specified probability density files have an extension .pdf and use an MDIF file format. Only a single distribution definition is allowed in each .pdf file.

Guidelines for .pdf

• In addition to the nominal value, there must be a minimum of three value/ordinate data pairs.
• For tolerance representation, all value data and the nominal value must have the same algebraic sign.
• The ordinate data associated with the most negative and most positive value data must be zero.
• All ordinate data must be non-negative.
• At least one non-end ordinate data must be non-zero.

Example PDF File

The following example shows how to create a user-defined PDF file. The technique involves the use of a discrete file which contains the nominal value and the statistical data (in piece-wise linear form.) In this example, the first block contains the allowable nominal values, and the second block contains the statistical information. The VALUE/ORDINATE pairs describe the user-defined PDF.

BEGIN DSCRD