[[File:RFSpice_Screen.png|thumb|400px|]]
[[RF.Spice ]] is the âRF Editionâ of [[B2.Spice A/D]]. In other words, it is an enhanced superset of the [[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.
At the heart of [[RF.Spice ]] lie the concepts of RF [[Transmission Lines|transmission lines]] and [[Multiport Networks|multiport networks]]. All the RF devices of RF. Spice can be divided into two groups: devices based on transmission line models, and devices based on multiple networks. As you will see in the later sections of this manual, [[RF.Spice]]'s transmission line models are based on SPICE's standard LTRA model. [[Multiport Networks]] 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 SPICEâs nodal admittance matrix formalism.
The S-parameter-based RF devices of [[RF.Spice ]] are primarily intended for use in two types of [[tests]]:
* AC Frequency Sweep Test
[[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==
The RF circuit analysis performed by [[RF.Spice ]] is based on the assumption that your distributed RF circuit can be modeled as an interconnected network of multiport devices and transmission line segments and components. This means that all the coupling or crosstalk effects must have been captured by the S-parameter-based models of devices or by the transmission line and discontinuity models used by [[RF.Spice]]. Most of these models work satisfactorily at lower frequencies up to several Gigahertz. At these frequencies, a quasi-static regime may be able to represent the physics of your RF circuit to a good level of accuracy. In the quasi-static regime, the different parts of your circuits can be treated as multiport devices or components that are governed by Kirchhoff circuit laws.
<p> </p>
[[B2.Spice_A/D -RF.Spice | Back to B2RF.Spice A/D Wiki Main Page]]
[[File:rarr.png]]
[[Multiport_Networks | Multiport Networks]]