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How to include exact 0 Hz (DC) point in PowerSI to avoid low-frequency extrapolation?

cistheta07

Hi Experts,

I am currently working on a high-speed PCB design that requires both Power Integrity (PI) impedance profiling and time-domain transient SPICE simulations. My analysis needs to cover the entire frequency range-from static  DC up to several gigahertz.

When I run standard AC S-parameter extractions in Hybrid Solvers, the solver extrapolates data at low frequencies (below 100 kHz down to 0 Hz). As a result, the low-frequency plane resistance (R_dc) isn't accurate, which distorts low-frequency die-bump impedance (Z_die) plots and results in miscalculated bulk decoupling capacitor requirements.

Additionally, if I run transient circuit simulations using these extrapolated models, my SPICE solver often experiences convergence issues due to non-physical DC offsets.

How can I configure PowerSI to include an exact 0 Hz static DC point in my S-parameter extractions so I don't rely on mathematical extrapolation?

Thankyou in advance.

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  • 0

    Hi Cistheta,

    Thank you for your question.

    When accurate DC-to-high-frequency behavior is required, relying on low-frequency AC extrapolation down to 0 Hz may not provide an accurate DC reference. PowerSI provides a DC–AC fitting feature that uses PowerDC to calculate the static DC solution and incorporates it into the S-parameter model.

    To obtain an accurate static 0 Hz reference in PowerSI, enable the Calculate DC point as reference option under:
    Tools → Options → Edit Options → Simulation (Advanced) → Field Domain → PowerDC Option

    Alternative: Merge Existing DC and AC Models

    If you already possess a standalone  DC model (from PowerDC or measurements) and a separate high-frequency AC S-parameter model (e.g., starting at ), you do not need to re-run the full EM extraction.

    PowerSI provides the Merge DC+Normal data feature, which allows the DC and AC datasets to be combined into a single S-parameter model.

    Please let me know if you have any further questions.

    Best regards,
    Alok

Reply
  • 0

    Hi Cistheta,

    Thank you for your question.

    When accurate DC-to-high-frequency behavior is required, relying on low-frequency AC extrapolation down to 0 Hz may not provide an accurate DC reference. PowerSI provides a DC–AC fitting feature that uses PowerDC to calculate the static DC solution and incorporates it into the S-parameter model.

    To obtain an accurate static 0 Hz reference in PowerSI, enable the Calculate DC point as reference option under:
    Tools → Options → Edit Options → Simulation (Advanced) → Field Domain → PowerDC Option

    Alternative: Merge Existing DC and AC Models

    If you already possess a standalone  DC model (from PowerDC or measurements) and a separate high-frequency AC S-parameter model (e.g., starting at ), you do not need to re-run the full EM extraction.

    PowerSI provides the Merge DC+Normal data feature, which allows the DC and AC datasets to be combined into a single S-parameter model.

    Please let me know if you have any further questions.

    Best regards,
    Alok

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