The designer’s job is to define these different sources for the component or subcircuit within the SPICE model file, which will then be assigned to a component or circuit block in your schematic.Ĭheck out our free ebook on 3D PCB Design and analysis here to augment your SPICE process. Components are defined using terminals, and the relevant terminals in your SPICE model should match the component pins you see on your schematic.Įach of these aspects of a SPICE model is defined using text with specific syntax. Sources can be modeled as dependent or independent sources.Ĭomponents: These receive input from a source or from the output of another component. Sources: These describe voltage/current sources in your circuit, which can be modeled as transients, piecewise linear, sinusoidal, pulsed, square, triangular, or sawtooth waves. In general, there are two types of SPICE models: With this in mind, let’s look at the anatomy of a SPICE model and how each SPICE model parameter relates to different types of simulations. In order to use SPICE models in any of these types of simulations, model parameters need to be defined for each of these domains. changes in input signal level (DC sweep or small-signal analysis), frequency, or time. Once your simulation finishes, you’ll receive a set of graphs showing electrical behavior vs. Your SPICE models are then used to build and solve a standard circuit model with a numerical technique. Creating simulations involving complex components requires defining the SPICE model parameters for each component in your schematic. If you’re using the right design software, SPICE simulations will start in your schematic after you’ve wired your components into circuits. Unfortunately, complex components may not include a SPICE model, and you will need to build a SPICE model for components if you want to use them in circuit simulations.
These models might define the impedance (e.g., for capacitors and inductors) as a function of frequency, which allows for AC simulations. Common components and passives usually have simple models that define the output voltage and/or current as a function of the input signals. Wouldn’t it be great if every component you needed included a SPICE model for instant circuit simulation? This is not always the case. If you’re building models for specialized components, you need to define model parameters from your component datasheets.Įach component in this layout will need a SPICE model for circuit simulations in the schematic. SPICE model parameters need to be defined for specialized components in order to simulate their electrical behavior. Every component that is used in a simulation has a SPICE model with a set of parameters that define electrical behavior.
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