Sonnet’s analysis engine, em, provides a frequency domain solution in the form of S- Y- and Z-parameters. Many time domain simulators, such as traditional SPICE engines, do not have the capability to import frequency domain data, or have problems with efficiency, stability, or accuracy when using frequency domain data.

To address these problems, Sonnet provides the capability to output your frequency domain data into a SPICE-compatible file. You may choose from four different models, depending on your needs. A brief description of each is provided below, and each model is discussed in detail in the sections following.

- Pi Model: Appropriate for circuits that are electrically small (less than 1/20 wavelengths) and can be represented by a simple Pi topology.
- N-Coupled Line Model: Appropriate for single or coupled transmission lines. Generates an RLGC matrix which can be used in the Cadence Virtuoso mtline element.
- Broadband SPICE Model: Appropriate for most circuits. Generates a lumped model based on a rational polynomial fit. Requires Broadband Spice Extractor license.
- Inductor Model: Appropriate for spiral inductors. Generates a simple lumped element model which is specific to spiral inductors. Requires Broadband Spice Extractor license.