Using Reduce Matrix Operations in Q3D Extractor

When you generate a solution, a row and column are generated in the capacitance matrix for each net in the model, while a row and column are generated in the inductance and resistance matrices for each source terminal in the model.

Reducing a model 's capacitance, inductance, and resistance matrices enables you to quickly and easily vary the excitations and connections of the conductors in your model without having to modify the conductor and source assignments and generate a new solution. In addition, it lets you model designs that cannot otherwise be simulated in Q3D Extractor — such as conductors connected in parallel or series. The reduced matrices can then be used to generate SPICE equivalent subcircuits for the model via the Make SPICE File command, and can also be input to other circuit simulation packages.

Reduce Matrix operations allow you to modify conductor definitions and generate new matrices containing fewer elements. Operations for Q3D Extractor include:

• Move Sink
• Add Sink
• Join in Series
• Join in Parallel
• Join Selected Terminals
• Float Net
• Ground Net
• Float Terminal
• Float at Infinity
• Return Path
• Change Frequency

Reduced matrices allow you to:

• Simulate series and parallel connections between nets or terminals.
• Model floating nets and floating terminals in a structure.
• Examine the effects of grounding different nets in a structure.
• For capacitance matrices, model the case where the charge at infinity is zero (that is, infinity is not held at zero potential).
• For AC problems, find the resistance at different frequencies.
• For inductance and resistance matrices:
• Change the location of current sink points within conductors.
• Add current sink points to multi-terminal conductors.
• Specify that current returns through a conductor in the model.

Based on these modifications, Q3D Extractor generates new matrices without computing new field solutions for any selected parameters that already have field solutions. This saves computing time and resources and allows you to easily optimize ground assignments when you generate a SPICE equivalent circuit.

You can select any object in the Modeler window and right-click, then select Assign Reduce Matrix. If the selected objects are valid terminals for the reduce matrix operation, they are considered for reduction; otherwise, they are ignored.

After reduction, reduced matrices and their Reduce Matrix operations appear in the Project Manager:

You can right-click the original or a reduced matrix in the project tree to see more options.

You can also right-click a Reduce Matrix operation and click Select Assignment to select the objects to which it applies.

Duplicating a Reduced Matrix

To duplicate a Reduce Matrix operation, right-click it in the Project Manager and select Duplicate.

Deleting a Reduced Matrix or Reduce Matrix Operation

To delete a reduced matrix or a Reduce Matrix operation, right-click it in the Project Manager and select Delete.