[[File:RFSpice_Screen.png|thumb|400px|]]
[[RF.Spice]] is the “RF Edition” of [[B2.Spice A/D]]. In other words, it is an enhanced superset of the EMAG Technologies' older [[B2.Spice A/D]] application with an extensive library of RF devices that include S-parameter-based [[Multiport Networks|multiport networks]] and a variety of generic and physical transmission line types. You can use [[RF.Spice]] to simulate or design distributed analog and mixed-mode circuits at high frequencies. The major differences between [[RF.Spice]] and [[B2.Spice A/D]] are: * 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 as well as 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, 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, when wave retardation effects start to appear. In other words, your circuit starts to act like a distributed structure rather than a lumped circuit where signals propagate instantaneously. In the analysis of a low frequency circuit, two nodes that are connected to each other through a wire are assumed to have equal potentials or identical voltages. In RF circuits, however, the connecting wires act as [[Transmission Lines|transmission lines]], whose lengths play an important role in determining the voltages and currents at different points of the circuit.
[[RF.Spice]]'s simulation engines are the same as the Berkeley SPICE and XSPICE engines of [[B2.Spice A/D]]. The high frequency AC analysis is carried out by the same analog and mixed-mode SPICE simulation engine. As a result, you can mix the RF devices in your circuits with all the other analog and mixed-mode devices of [[B2.Spice A/D]]. You can also mix transmission-line-type RF devices with digital parts and perform mixed-mode time domain simulations.
From a simulation point of view, an RF circuit is made up of a collection of [[Multiport Networks|multiport networks]] that are interconnected via RF [[Transmission Lines|transmission lines]]. If the input of your circuit is connected to a source and its output is connected to a load, then you can compute all the voltages and currents at all the external or internal ports of the circuit (i.e. at the various circuit nodes). Or you can calculate the port characteristics of the overall network by designating input and output ports to your RF circuit.
==Limitations of RF.Spice==