Using LineCalc

LineCalc is an analysis and synthesis program for calculating electrical and physical parameters of single and coupled transmission lines.

LineCalc can communicate directly with the circuit simulators. You can send parameter data for selected circuit design elements, along with data on any associated substrates or walls, directly from the simulator to LineCalc. After the element parameter values are calculated, you can update the associated schematic or layout circuit design in the active simulator immediately with the LineCalc results. Or you can place a newly synthesized component into the Schematic window.

Using dialog boxes, you can make changes in parameter values of your transmission lines and see the results of those changes on the screen. You can use LineCalc like a spreadsheet, in the sense that a change in one value brings about a recalculation through all related values when you choose the appropriate Calculate button.

You can print results, save results to an element data file, or instantly update a schematic or layout in a circuit design.

Note LineCalc cannot be used with the signal processing simulators.

The Basic LineCalc Process

• Select a LineCalc component.
• Select one or more independent parameters for calculation.
• Change default parameter values, as necessary.
• Perform the analysis or synthesis.
• Update the design, if applicable.

Key Terms

Analysis Calculation of electrical parameters from physical data.

Synthesis Calculation of physical parameters from electrical data.

Shared Parameters Parameters common to a group of components and required for both analysis and synthesis.

LineCalc File (<filename>.lcs ) The data file created when results from a LineCalc analysis or synthesis of a component are saved. The file contains information about the component's parameters, associated shared parameters, frequency, and units to support design iteration.This data file is created when you save results from a LineCalc analysis or synthesis of a component. The file contains information about the component's parameters, associated shared parameters, frequency, and units to support design iteration.

Starting LineCalc

Before running LineCalc, you should be familiar with the basic operation of the ADS design environment. (For details, refer to the Schematic Capture and Layout manual.)

To run LineCalc from within the Design Environment:

• From the Schematic window, choose Tools > LineCalc > Start LineCalc .
  To run LineCalc in stand-alone mode:
• On the PC, from the Start menu choose Programs > Advanced Design System 2006A > ADS Tools > LineCalc .
• On UNIX, in a terminal window, type linecalc .
  

  Note Starting LineCalc in this manner assumes you have established a path to the ADS installation directory. If you have not, type <install_dir>/bin/linecalc , where <install_dir> represents your complete installation path. For details on establishing a path statement, refer to Chapter 2 of the UNIX and Linux Installation manual.

  When LineCalc is launched, the LineCalc window appears, as well as the Message/Status window. The Message/Status window displays messages about the status of the current process as well as warning messages.

The LineCalc Window

The LineCalc window is divided into several regions.

• Title Bar, Toolbar, and Menu Bar

• Component Display

• Shared Parameters Display

• Parameters Display

• Results Display

• Status Bar

The following sections describe these regions.

Title Bar, Toolbar, and Menu Bar

The Title bar displays the application name and the name of the active data file (or untitled if no data file is associated with the data being displayed).

The Toolbar contains buttons for frequently-used commands.
The Menu bar displays the available menus and commands.

Component Display

The Component display lists the currently-selected component type and ID. You can choose a different component type and ID to analyze or synthesize, by the Selection arrow .

Shared Parameters Display

The Shared Parameters display consists of the Substrate Parameters and the Component Parameters sections. The parameters shared by all components with substrate parameters are listed in the Substrate Parameters area. The parameters shared by components with frequency or mwall parameters are listed in the Component Parameters area.

Parameters Display

The Parameters display lists the physical and electrical parameter values of the currently-selected component.
In the Physical section, the Fix button indicates the status of the associated physical parameter:

• If the button indicates Fixed, the adjacent parameter is fixed during synthesis
• If the button indicates Fix, the adjacent parameter is updated during synthesis
  You can compute the physical parameter values from electrical data by clicking Synthesize .
  and clicking Analyze computes the electrical component parameters from physical data.
  

Results Display

The Results display shows the parameter values that change as a result of the synthesis or analysis. These are displayed as the calculated results.

Status Bar

The Status Bar at the bottom of the window shows the status of your displayed data. When you have changed a parameter value without recalculation (synthesis or analysis), the message appears: Parameter(s) modified - Values are not consistent. After you perform the calculation, the message appears: Values are consistent .

LineCalc Menus and Commands

This section describes the LineCalc Menus and Commands. The LineCalc User Interface has the following menus:

• File Menu
• Simulation Menu
• Options Menu
• Help Menu

Changing the Default Data Directory

The LincCalc program reads the files from and save these to your program startup directory, unless you change the default directory.
To use an alternate directory during your current program session:

1. From the Synthesis/LineCalc window, choose File > Change Dir.
2. Use the displayed dialog box to specify a directory path (other than the program startup directory) for reading and saving files until you exit the program.

Resetting the Display
You must clear any currently active work before selecting or importing components for a new synthesis or analysis.

• To save your work, choose File > Save ; then choose File > New .
• To cancel a design in progress and start over, choose File > New .
  

  Note Choosing New displays the default component.

Opening a Component File

After resetting the display, you can activate a component that you want to synthesize or analyze in one of these ways:

• By opening a previously-saved LineCalc component file, or
• By importing components from the active schematic or layout design

  Note When you activate LineCalc, the last-saved component is displayed. Clear the display before opening a component file (see Resetting the Display).

Opening a Previously-Saved LineCalc Component File

You can activate a component that you want to synthesize or analyze by opening a previously-saved LineCalc component file.
To open a previously-saved LineCalc component file:

1. Choose File > Open to display the dialog box.
   
2. Specify the path to the directory where the component file is located. Click Filter to activate a list of data files in the specified directory. This step may not be necessary if the file is located in your current directory or if you changed your default data directory.

   Note Choosing a file from a different directory does not change the default directory.

3. In the Data Files list, select the component file. The component data saved to that file becomes active in the LineCalc window.

Importing Components from the Active Design

You can activate a component that you want to synthesize or analyze by importing components from the active schematic or layout design.
To import components from an active design:

1. In the Schematic or Layout window, select the component you want to send to LineCalc. In the illustration, a portion of a schematic example, MLIN:TL2 is selected.
   

   Note You can send only one component at a time.

   
2. Choose Tools > Send Selected Components to LineCalc . The component data for all selected components is sent to LineCalc.

In the LineCalc window, each component that you import from the Schematic or Layout window, along with its ID name, is listed in the Component ID Selection dialog box. In the illustration the two MLINs (TL2 and TL3) that were sent to LineCalc from the Schematic window are now displayed in the Component ID Selection list and can be selected for evaluation.

Only one component/ID calculation can be performed at a time. For example, select and perform any calculations on MLIN:TL3 before you attempt to select and modify MLIN:TL2.

Selecting a Component

Note Before selecting or importing components to begin a new synthesis or analysis, be sure to clear any currently active work. See Resetting the Display".

To select a component:

1. In the Component ID field, click Select to display the dialog box. The LineCalc window changes to display the active Component Type, Component ID, parameters, and other data.
   
2. Select the component you want displayed and click OK to accept the component and dismiss the dialog. Click Apply to accept the component and keep the dialog open.

Displaying Component Help

To display detailed information for a component, select Help > What's This? and place the question mark on the component illustration.

Changing Default Units

You can modify program units or frequencies before calculating the results by setting the Frequency, Length, Resistance, and Angle units.
To modify default units or frequencies:

1. In the Menu bar, select Options > Preferences. Change the default unit preferences by selecting from the drop-down lists. Default Units lists program options.
   

   Unit	Options	Default
   Frequency	GHz, MHz, kHz, Hz	GHz
   Length	in, mil, m, cm, mm, um	mil
   Resistance	kohm, ohm	ohm
   Angle	deg, rad	deg

2. In the Units display, modify the settings and click OK to accept your changes. The newly-chosen unit is reflected when a new component is chosen.

Changing Parameter Values

To change any values in the Physical or Electrical parameter fields:

• Select the value and type a new value in the field.

To change Shared parameter values:

• Select the default value and type a new value in the field.
• To change the units associated with each shared parameter, select the units button next to each parameter field.
  

  Note See also: Interdependent Values for Electrical Parameters and Fixed Values for Physical Parameters

Interdependent Values for Electrical Parameters

For certain components, some of the electrical parameter values depend on the current values assigned to other parameters. In the following illustration, note the beginning values for ZO and Z0 in the Electrical portion of the Parameters display for the MCLIN component.

To observe the values of related parameters change automatically, change the value of ZO to 22 and press Enter (or click one of the other fields containing interdependent parameters).

The display updates to show that the corresponding Z0 value changed from 48.815 to 38.099. Also, the C_DB value changed from −10.676 to −6.022. Generally, the last two visited fields are used to compute the other parameters.

Fixed Values for Physical Parameters

Certain components require the value of one of the physical parameters to be fixed (not modifiable) during synthesis. For these components, one parameter must be assigned a fixed value before you can perform a synthesis. For example, observe how the W and G parameters of the CPW component are interrelated. By default, when you select the CPW component, the value of G is fixed and the value of W is not. This default condition is shown by the label on the Fixed button, which is dimmed.

If you want to change the value of G, you must click the Fix button for W. The new condition is shown by the label on the button which changes to read Fixed and is dimmed. An active Fix button on the G value indicates that value is currently not fixed and will change during synthesis.

Performing a Synthesis

A synthesis computes the physical parameter values based on the electrical parameter values.
To synthesize a revised component:

• Select Simulate > Compute Physical Params or click Calculate (Up button) in the Parameters display. The values for physical parameters (shown in the upper portion of the display) are computed from the electrical values and the values in the Results display are updated.

Performing an Analysis

An analysis computes the electrical component parameters based on the physical parameter values.
To analyze a revised component:

• Select Simulate > Compute Electrical Params or click Calculate (Down button) in the Parameters display. The values for electrical parameters (shown in the lower portion of the display) are computed from the physical values and the values in the Results display are updated.

Updating Schematics with LineCalc Results

After performing a synthesis or analysis, you can place the component to the Schematic window.

In the Schematic window, select Tools > Linecalc > Place New Synchronized Component.

If you start LineCalc from the Schematic and send selected components to LineCalc for synthesis or analysis, you can update your schematic when your calculations are complete.

In the Schematic window, select the component to be updated. Then select Tools > LineCalc > Update Selected Component From LineCalc .

Saving Results

To save a LineCalc component file:

• Choose File > Save from the Synthesis/LineCalc window. The program automatically saves the filename with an .lcs extension. Unless you change the default data directory, the data file is saved in the program startup directory.

To save a LineCalc component file to a different data file:

1. In the Synthesis/LineCalc window, choose File > Save As .
2. In the dialog box, enter a filename and specify a directory path.
   To save a design that was modified by LineCalc calculations:

• In the Schematic or Layout window, choose File > Save .

Printing

You can print the data for a component.

• To specify a printing configuration, choose File > Print Setup .
• To print the data associated with the currently displayed component, choose File > Print.

The printed data format is:

product information

date information

component type

component ID

units information

frequency value

shared parameters

physical parameters

electrical parameters

result parameters

Note For detailed information on print and print setup options, refer to your operating system documentation.

Exiting the Program

To exit LineCalc:

1. Choose File > Exit. If any unsaved changes are detected, you are prompted, Do you want to save the design?
2. Select Yes or No , as appropriate.
   If you select Yes , and the currently active file had not been saved previously (that is, labeled untitled at the top of the window), the Save As dialog box appears, prompting you for a filename.

Using AEL Commands

Using the program's Applications Extension Language (AEL), you can create entries for user-defined components, customize the contents of library and palette menus, and write customized commands. For configuration details on using AEL, see the AEL manual.

To execute AEL commands:

• Choose Options > Command Line to open the Command Line dialog.

• Type the command(s) in the Command >> field or select one of the commands in the Command History list. Click Apply to execute the command. You can double-click a command in the list to select and execute it.
  

  Note All commands entered in the Command >> field must be in correct AEL format.

Using Macros to Automate Tasks

Creating a Macro File

To create a macro file:

• Using any text editor, create a file in one of your project directories and type the lines containing the AEL functions you want to execute. The filename must have the extension .ael .

Recording a Macro

To record a macro:

• Choose Options > Command Line to open the Command Line dialog.

1. Select Options > Start Record Macro . In the dialog, enter a filename for the macro file you are going to record and choose OK to close the dialog.
   
2. In the Command Line dialog, the Command History displays all actions taken in the LineCalc window during the recording. Alternatively, enter the AEL functions you want to record in the Command >> field.
3. Select Options > Stop Record Macro to stop recording.

Running a Macro from the Design Environment

To play back a macro:

1. Choose Options > Playback Macro . A dialog displays all the .lcm files in the current project directory. You can browse to display macros from another directory.
   
2. Select the macro you want to play back and click OK to execute the selected macro.

Running a Macro from the UNIX Command Line

To run a macro file from the UNIX command line:

• Change directories (cd) to your working directory and type:

  $ linecalc -m <filename>.lcm

  or

  $ linecalc -m synthesize.lcm