Output voltage for a filter with 50 Ohm input and output matching resistors. This figure includes a plot of the small signal AC The syntax of the subcircuit netlist listed in Figure 3.1 is only understood by Qucs and cannot be read without error by external SPICE simulators.įigure 3.1 Qucs 15MHz centre frequency band pass passive filter subcircuit without parametersĪ test bench circuit for simulating the band pass filter circuit shown in Figure 3.1 is given in Figure 3.2. (2) a subcircuit symbol, and (3) a Qucs netlist giving a list of the internal components, their connection nodes and a wrapper whichĭefines the subcircuit. Note that the threeĭistinct parts of a subcircuit model without parameters are: (1) a circuit representing the model body with one or more input (Pin) and output (Pout) pins plusĬonnected components selected from Qucs pre-defined components and user designed subcircuits ( there are no user defined subcircuits present in Figure 3.1),
This introduction isįollowed by a detailed description of the structure, and netlist syntax, of subcircuits with one or more parameters.ģ.1.1 Spice4qucs subcircuits without parameters ¶įigure 3.1 shows a Qucs subcircuit model for a 15MHz centre frequency band pass passive filter. However, an optional part of the Ngspice, Xyce and SPICE OPUS subcircuit netlist syntax that signifies that a parameterĮxtension is present is not allowed (see section 3.1.2).Īs a starting point spice4qucs subcircuits without parameters are considered first. In a similar fashion to Qucs, the Ngspice, Xyce and SPICE OPUS circuit simulators allow subcircuits with or without parameters. Spice4qucs supports all the features available with Qucs subcircuits. This is not surprising because they formĪ natural way of breaking an electonic system down into a number of smaller self contained functional blocks. Today, all practical circuit simulators have subcircuits as part of their basic device compliment. Subcircuits are a concept that has been part of established circuit simulation practice since the early days of computer aided circuit design. Qucs-S/Octave circuit simulation and device parameter extraction interfaceģ.1 Spice4qucs Subcircuits: with and without parameters ¶ RF simulation with Ngspice, Xyce and SPICE OPUS Verilog-A compact semiconductor device modelling Introduction to mixed analogue/digital simulation XSPICE user written device models and library Qucs and SPICE simulation models that work with ngspice, Xyce and SPICE OPUS Ngspice, Xyce and SPICE OPUS post-simulation data processing with Qucs-S and Octave More advanced circuit simulation techniques.
Device and component modelling with algebraic equations 3.4.2 Symbol pattern files format description.3.4 Usage of unmodified SPICE Libraries.3.3 Using manufacturers component data libraries.3.1.3 A second more complex example of Spice4qucs subcircuits with parameters.3.1.2 Spice4qucs subcircuits with parameters.