Using a PWL current source in Clarity 3D Layout with Spatial Mode

Clarity3DWorkbench and Clarity3DLayout support 3D Full Wave Spatial Mode simulation. This 3D full wave spatial mode is a workflow inside the tool.

The main application of spatial mode is to be able to view the voltage distribution, far field radiation, and near EM field distribution of a 3D structure (such as RF chip, chip RDL, package, or PCB) excited by one or multiple I-sources directly at the ports. The spectral content that is generated for the pulse/pwl source is solved using the discrete frequency sweep and the fields and mesh are saved at these frequency points

On many occasions, it is necessary to use I-Source for a port in the simulation setup of Clarity 3D when used in Spatial mode. 

You may want to use a PWL current source file instead of using the GUI-based current source definition, which is a static current definition.

Here is how you can do it.

Piecewise linear waveform (PWL) only contains time and the corresponding voltage or current value for each row. In other words, column one is time and column two can either be current or voltage. It is simply the I-T or V-T curve data.

We can see a sample Current plot for a DQ net of a DDR design captured here in text.

To use this in the Spatial mode simulation of Clarity 3D Layout, you should add the subckt definition in the first line and encapsulate the entire PWL data with spice format.

Here is the edited PWL data in the txt file, with the spice subckt definition on line 1 and an i element (current source) connected in line 2. In the last line, the end statement is put in.

After preparing the PWL file for spice format, you can load the file in the Current Source File section.

Shown below is the PWL file setup in Clarity:

Here, select the PWL file by clicking on the >>.

The port1 is using a  ISOURCE in the Current Source section.

After assigning the PWL file you can click Refresh in the bottom-right corner of the Current Source Viewer dialog.

The above current source data in time-domain is now transformed into frequency domain, using FFT.  The amplitude at various frequencies up to 3Ghz is displayed for the PWL current source.

You are now ready to perform the Spatial mode simulation in frequency domain but using the time domain PWL current data points