Changes

Multiport Network device, i.e. one-ports, two-ports, three-ports and four-ports, are all modeled based on their frequency-domain S-[[parameters]]. Most active and passive RF devices can be modeled as multipart networks. For example, RF diodes can be modeled as one-ports, while RF transistors (BJTs, JFETs, MOSFETs, and MESFETs) can be modeled as two-ports. Many semiconductor manufacturers publish S-parameter data sets for their RF devices. The manufacturer data sheets usually contain S-[[parameters]] in Mag/Phase format tabulated as a function of frequency expressed in GHz. On the other hand, you can model many passive devices such as filters, directional couplers, hybrids, etc. as multiport structures using full-wave electromagnetic simulators like [[EM.Cube]]. The port characteristics of such devices are typically written into data files as a function of frequency. A particular case of interest is transmission line components with complex geometries or material composition, for which [[RF.Spice ]] does not provide any database models. as an example, consider the case of a "Finline" transmission line. In a finlike-based circuit, you may need one of more of the following general transmission line components:

[[RF.Spice ]] allows you to import S-parameter-based models of RF devices from text files. Before describing how to import S-parameter data files, let us first discuss the format of the data files in more detail. S-parameter data files must have a ".TXT" file extension. These files must start with a ".model", a ".symbol" statement, and a format statement starting with the character "#". The model text file can have any number of comment lines at the beginning of the file or elsewhere. Comment lines are preceded by "*" or "!". All the text after these characters on the rest of the line will be ignored. 

freq     s11 s21 s31 ...     s12 s22 s32 ...     s13 s23 s33...

3.000   0.7449   110.9   0.985   15.5   0.1475   41.9   0.4218   -93.3

| RF BJT || bjt_npn bjt_npn_2port <br /> bjt_pnp bjt_pnp_2port || two-port || [[File:G11G11A.png]]

The first item in the above list simply lets you import an S-parameter ".TXT" file and saves it as a simulation model in [[Network_Analysis_of_RF_Circuits | Back RF.Spice]]'s parts database. You can use this model later to Network Analysis build a new device or share it among several devices. The next three items in the above list create new devices complete with simulation models and schematic symbols. The newly create devices are permanently stored in your [[RF.Spice]] parts database and can be used as new parts in your RF circuits. For example, an imported RF BJT device has the same BJT symbol with the same pin map as the other BJT devices of [[B2.Spice A/D]]. The main difference is that instead of a technology process models or a Netlist subcircuit model, the RF CircuitsBJT is modeled by its imported, measured S-[[parameters]]. In a similar manner, you can import Multiport Network devices or T-Line Discontinuity models from S-parameter text files that are generated at the end of full-wave simulations of such structures using an electromagnetic modeling tool like [[EM.Cube]]

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