Once a designer completes their model and calculate RLCG of all sinks and sources, they might be interested to know RLCG if some sources or sinks are connected together. Q3D Matrix Reduction helps the designers to achieve this goal.
It usually happens when some parts are electrically connected in series or parallel. The Join in Series reduction lets you connect the sink terminals of one or more conductors in series with a source terminal on a different conductor. The connected conductors are then treated as if they were a single net. The rows and columns that represent their contributions to the matrix are replaced with a single row and column representing the contribution of this new object.
The Join in Parallel reduction lets you connect two or more source terminals, which are then treated as if they were a single object. The rows and columns that represent their contributions to the matrix are replaced with a single row and column representing the contribution of this new object.
In below video, join in parallel is shown. In the next video, return path is also shown as some designers would be interested in modeling that and finding equivalent RLCG model. There are other options available such as Float Terminal, Float at Infinity, and Float Net.
The software directly solves for partial inductance and resistance matrices, and they are shown in the video.