As described in Introduction to DVM,
managed-source and managed-load symbols can represent any number of different
electrical definitions, depending on the test objective of a particular
simulation. While the source and load symbols do not visibly change, the
electrical definition of the subcircuit called by the symbol does change.
For example, DVM can change the subcircuit used by a managed load symbol
to do the following:
- Represent a simple load resistor
- Exhibit special transient behavior, such as change a pulsed load
to simulate a load transient
- Include an injected AC source and the Bode plot probe required
for measurement in an AC Bode plot analysis
Likewise, a managed source subcircuit can do these things:
- Represent a constant DC voltage source
- Represent a start-up ramp or a pulsed line voltage source
- Perform input impedance measurements by including components that
inject an AC small signal perturbation into the circuit and measure
the resulting input impedance
Configuring DVM Sources and Loads
You define which sources and loads are managed using the SIMetrix/SIMPLIS DVM Control
Panel that opens when you double click on the DVM control symbol.
After selecting the sources and loads to manage, the reference designators (V2,
I1, in this example) are saved to the DVM control symbol. You then need to edit
the default specifications for the managed sources and loads. For more information, see
the DVM Tutorial 3.1 Editing the Schematic topic.
Custom subcircuits can be designed as schematic components and then converted to ASCII
models to be used with DVM.
Adding a New DVM Source or Load
Adding a source is described here, but the process of adding a load
is exactly the same. The design starts with V2
and I1 as the source and load
- Select the number of new sources and loads from the Circuit Specifications page of
the control symbol dialog. For this example, select 2 from the Number of DC
Inputs drop-down menu.
Result: The page selection box on the left side
is populated with two DC input source entries:
- Select the second DC input source and enter the source voltage and resistance
Note: DVM automatically finds all DVM input source and load symbols and if
you have already placed a source or a load symbol, you can select the reference
designator from the drop-down box shown above. Otherwise, DVM automatically enters
a source/load placement routine after you accept the dialog in the next
- After entering the parameters, click Ok to accept the dialog.
Result: DVM has detected that you wish to add a source to
the design. A messagebox opens alerting you to this:
- Click Ok, and place the new input source on the schematic.
Result: DVM adds the source information to the control symbol:
Adding an Existing DVM Source or Load
If you have already placed a DVM source or load on the schematic, you
can easily add it to the DVM managed sources or loads. In this example,
assume that reference designator V_12
was already palce on the schematic and you want to manage this source
- Double click on the control symbol...
- Select the new number of sources to be 2:
- On the DC Input 2 page, select the V_12 reference designator:
- Click Ok.
Result: The control symbol now lists both
the V2 and V_12 designators.
Removing Managed Sources or Loads
To remove a managed source or load, follow these steps:
- Double click on the DVM control symbol.
- In the page-selection box, select the source or load that you
want to remove.
- Click Circuit Specifications, and change the number of inputs or
- Click Ok to save the new
Changing a Source or Load Subcircuit Definition
You change a source or load subcircuit definition using the Source
and Load testplan entries.