An Overview of RF.Spice
RF.Spice is the “RF Edition” of B2.Spice A/D. In other words, it is an enhanced superset of B2.Spice A/D with an extensive library of RF devices that include S-parameter-based multiport networks and a variety of generic and physical transmission line types.
The major differences between RF.Spice and B2.Spice A/D are the following:
- The RF.Spice Workshop has an additional RF Menu with a large collection of RF parts.
- The RF.Spice Device Editor has an additional RF Menu with a variety transmission line calculators and designers and utilities for importing active and passive S-parameter-based RF device models.
- The RF.Spice parts database is a superset of the B2.Spice A/D parts database.
- The node-locked licenses of the two programs are different.
RF Circuit Analysis
RF circuit analysis, by nature, is an AC analysis that you typically run at high frequencies ranging from tens of Megahertz to tens of Gigahertz. At such high frequencies, the dimensions of your circuit may become comparable in order of magnitude to the wavelength, and wave retardation effect start to appear. In other words, your circuit starts to act like a distributed structure rather than a lumped circuit where the signals propagate instantaneously. In the analysis of a low frequency circuit, two nodes that are connected to each other trough a wire are assumed to have equal potential or identical voltages. In RF circuits, the connecting wires indeed act as transmission lines, whose lengths play an important role in determining the voltages and current at different point of the circuit.
The RF devices of RF. Spice are characterized and modeled based on their frequency-domain scattering (S) parameters. The S-parameters are tabulated as a function of frequency and interpolated in between the frequency samples. RF.Spice performs an AC analysis of these RF devices by converting their S-parameters to Y-parameters and using them in conjunction with the SPICE’s nodal admittance matrix formalism. As a result, you can mix RF devices with all the other analog and mixed-mode devices of B2.Spice A/D in your circuits.
The RF devices of RF.Spice are primarily intended for use in two types of tests:
- AC Frequency Sweep Test
- Network Analysis Test
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RF devices do not work with “Live Simulation” or Transient Test as their models normally contain S-parameters at high frequencies only. |
At the heart of RF.Spice lie the concepts of a multiport network and a generic transmission line.
