GenerateInitFile

Schematic Configuration

This example schematic uses a simple L/C oscillator to demonstrate the generation and inclusion of initial conditions files. The capacitor has a schematic initial condition of 1.0V, this initial condition is used when no initial conditions file is included. For tests where an initial conditions file is included in the simulation, the included initial conditions override the schematic initial conditions.

The Multi-Step analysis parameter name and the values are set on the schematic's DVM Control Symbol, in this example, the FBASE parameter is stepped over three values. The "Save state" checkbox is checked, which tells SIMPLIS to generate an array of initial conditions files, one for each stepped parameter value:

• FBASE=900k
• FBASE=1Meg
• FBASE=1.25Meg

The inductor value L is calculated from FBASE in the schematic's F11 window.

The Monte Carlo simulation is setup on the DVM Control Symbol to run 8 steps with a starting seed value of 123. The "Save state" checkbox is checked, which tells SIMPLIS to generate an array of initial conditions files, one for each Monte Carlo seed value.

Testplan

The testplan for this example is included in the zip archive: init_files.zip, and is shown below is a table.

A test-by-test explanation is as follows:

init_files.single.init

three_frequencies,multi-step

three_frequencies.init_files_FBASE=900k.init
three_frequencies.init_files_FBASE=1Meg.init
three_frequencies.init_files_FBASE=1.25Meg.init

Monte Carlo

Two examples of generating and including initial conditions files are demonstrated in this testplan. The first example uses the DVM Control Symbol values for the Monte Carlo, namely, eight steps and a starting seed of 123. The generateinitfile entry of:

eight_steps_seed_123,montecarlo

generates these eight initial conditions files:

eight_steps_seed_123.init_files_123.init
eight_steps_seed_123.init_files_2067261.init
eight_steps_seed_123.init_files_337175501.init
eight_steps_seed_123.init_files_384717259.init
eight_steps_seed_123.init_files_613744155.init
eight_steps_seed_123.init_files_834051741.init
eight_steps_seed_123.init_files_1281840491.init
eight_steps_seed_123.init_files_2017191533.init

The next test includes these files in the simulation. The second example is similar, except it uses four steps and a starting seed of 3000. The initial conditions files generated are unique and will not conflict with the earlier Monte Carlo example in which eight steps were run from a starting seed of 123.

Single Simulations

The first form is used for a single step simulation. When textstring is placed in a GenerateInitFile column, the program will make a copy of the .init file generated by SIMPLIS, and save that file to the DVM_SUPPORT directory. The file will have the following naming convention, where <schematic_name> is the name of the schematic, and textstring is the entry in the DVM testplan:

<schematic_name>.textstring.init

Tests which have a IncludeInitFile entry with textstring as it's entry will include this initial conditions file.

Multi-Step and Monte Carlo Simulations

Starting with version 8.10e, DVM supports generation and inclusion of an array of initial condition files for Multi-Step and Monte Carlo simulations. In order to use this feature, you must check the "Save state" checkbox on the DVM Control Panel for either Multi-Step or Monte Carlo simulations. This directs the program to name the initial conditions files with the stepped parameter values for a multi-step analysis or the seed value for a Monte Carlo analysis. Additionally, for a Monte Carlo analysis, you must provide a seed value, as this guarantees the simulation will use the same seed values for both the test which generates the init file and the test which includes the file. The syntax is as follows:

• textstring,multi-step
• textstring,montecarlo

In this form, textstring is any text, and multi-step and montecarlo are special keywords. Note that the text string to identify the initial conditions files and the keyword are separated by a comma. These two entries instruct DVM to make copies of all .init files generated during the Multi-Step or Monte Carlo simulation, and save these files into the DVM_SUPPORT directory.

The filenames generated by the program will be determined by the stepped parameter values, or the Monte Carlo seed values. For a multi-step simulation where FBASE is stepped over three values:

• FBASE=900k
• FBASE=1Meg
• FBASE=1.25Meg

SIMPLIS will create three initial conditions files and the generateinitfile entry of:

textstring,multi-step

will generate these three files in the DVM_SUPPORT directory:

textstring.<schematic_name>_FBASE=900k.init
textstring.<schematic_name>_FBASE=1Meg.init
textstring.<schematic_name>_FBASE=1.25Meg.init

For nested multi-step simulations, the created filenames will include each parameter value with an underscore separating the parameter name/value pairs. No additional actions are required to use this syntax for nested multi-step.

Files created during a Monte Carlo simulation will have the seed values included in the filename where the stepped parameter values are located in the above filenames. One .init file will be generated for each Monte Carlo step.

Multi-Tone AC Analysis Simulations

This form of entry is only used for the Multi-Tone AC analysis and it requires you to run an AC analysis test objective. The Multi-Tone AC Analyses use special sources and loads to inject multiple frequencies into the circuit under test. The initial conditions file needs to be "keyed" to these injection values. There are five relevant parameters:

1. start frequency
2. end frequency
3. injection amplitude
4. sweep type
5. number of frequencies

The generateinitfile entry of

textstring,multitoneac

<schematic_name>.textstring^<start frequency>^<end frequency>^<injection amplitude>^<sweep type>^<number of frequencies>.init

As the linear sweep doesn't use the number of frequencies entry, this is omitted from the init filename.