Use extracted InductEx® values in a JoSIM circuit

Before starting

Use complete writable copies of the supplied microstrip example and a working licensed InductEx®/JoSIM installation. Put microstrip.ixi, microstrip.cir, microstrip.gds and process.ldf together in a new folder. Keep the installed example and earlier results as references.

The checked path uses InductEx® 8.0.1 Windows CLI and the recorded JoSIM®-Pro 2.9 review CLI. Automatic back-annotation requires the entitlement accepted by that InductEx® release; current source permits SUPER and QUANTUM. An ordinary extraction finishing does not establish permission to write an annotated deck.

For the Studio extraction controls, follow the linked first-microstrip guide. The commands below assume the matching CLIs are available on PATH; otherwise use their quoted absolute executable paths.

Keep the two circuit roles distinct

The InductEx® circuit describes extraction branches and excitation ports. The JoSIM deck describes an actual circuit with sources, devices, analysis and outputs. Map element names and node orientation deliberately; extraction port declarations are not ready-made JoSIM simulation devices.

Read the Extracted column and its header unit in the new solution. For this case the header is Inductance [H]. A value of 3.89648 pH is 3.89648e-12 H. Keep the design value separate from the extracted value.

A merged series branch determines a combined impedance; do not assign that total to every listed component. For coupled models, keep orientations and topology consistent. A mutual inductance M in henry is not the dimensionless JoSIM K coefficient; for positive self-inductances the conversion is k = M / sqrt(L1*L2), and the complete coupling group must be physically valid. This example exercises one uncoupled branch.

Create the JoSIM template

Save the following as transfer.cir beside microstrip.ixi. LTRANSFER is the target element. The current source injects current from ground into A; the inductor carries it from A to ground. The initial 3.9e-12 H is a placeholder to be replaced by extraction.

* Extracted microstrip branch: current-ramp sanity check
IIN 0 A PWL(0 0 10p 0 30p 1m 50p 1m 70p 0 100p 0)
LTRANSFER A 0 3.9e-12
.TRAN 0.1p 100p
.PRINT V(A) I(LTRANSFER)
.END

Map the branch in microstrip.cir

1. Replace the copied microstrip.cir with the small extraction netlist below. Keep the supplied port mapping; [LTRANSFER] names the target simulation element.

* Extraction branch and layout ports: microstrip.cir
L1 1 2 3.9e-12 [LTRANSFER]
P1 1 0
P2 2 0
.END

Request back-annotation in microstrip.ixi

1. Add the following block at the top level of the copied microstrip.ixi. The transfer.cir template must already exist in the project folder.
2. Use a fresh output directory for each attempt. The checked command belongs in the IXI file. An older netlist .control example is ignored by the checked 8.0.1 runtime.

$CONTROL
  BACK-ANNOTATE "transfer.cir"
$END

Extract and simulate the new deck

1. Run InductEx® from the working project folder and inspect its errors, warnings and current output/sol.txt.
2. Confirm output/transfer_annotated.cir exists and contains the mapped LTRANSFER value. Compare it with the fresh solution and diff it against transfer.cir. The template should remain unchanged.
3. Run the annotated deck in JoSIM and write its waveform to a separate CSV filename. Read the time, V(A) and I(LTRANSFER) columns.
4. Copy the annotated deck to transfer_refined.cir, change only .TRAN 0.1p 100p to .TRAN 0.05p 100p, then run it to transfer_refined.csv. Keep both results.

inductex microstrip.ixi
josim-pro-cli -o transfer.csv output/transfer_annotated.cir
# After copying and editing the refinement deck:
josim-pro-cli -o transfer_refined.csv transfer_refined.cir

Check the transferred parameter and waveform

The checked extraction printed L1 = 3.89648e-12 H. The annotated deck retained more digits: LTRANSFER A 0 3.896479063E-012. Compare with the solution at its printed precision; the extra annotation digits do not establish physical accuracy.

The source rises from 0 to 1 mA in 20 ps. For this ideal branch, V = L*dI/dt gives approximately +0.194824 mV during the rising ramp, zero on the constant-current plateau and -0.194824 mV during the falling ramp. CSV time, voltage and current are in seconds, volts and amperes.

Both tested time steps produced finite data over 0–100 ps: 1,001 samples at 0.1 ps and 2,001 at 0.05 ps. The analytic comparison used windows 15–25 ps, 35–45 ps and 55–65 ps, away from waveform corners. Its local criteria were voltage error below 0.1% of ramp amplitude and current error below 1 nA. These criteria check this ideal-parameter handoff; they are not extraction accuracy or universal circuit tolerances.

A successful transfer does not establish mesh convergence, the validity of an entire compact model or behaviour beyond its frequency/temperature assumptions. Review those separately before substituting an extracted network into a production circuit.

Recover from missing or unexpected output

If the annotated deck is missing, read the exact warning first. Check the IXI command location, template filename, target [LTRANSFER] mapping, output directory and entitlement. The related troubleshooting answer covers the ignored legacy command.

If the value remains the placeholder, inspect the source-to-target mapping and the actual deck you opened. If JoSIM rejects the circuit, use its diagnostic to check source syntax, units, node references and the complete coupling model. Preserve the extraction solution, template, annotated deck and run settings when requesting help.