Performing an AC Simulation

An AC simulation is performed in the frequency domain. You can simulate a single frequency point, or across a frequency span in a linear or logarithmic sweep.

To perform an AC simulation, create your circuit, then add current probes and identify the nodes from which you want to collect data.

For a successful analysis, be sure to:

• Add the AC simulation component to the schematic. Double-click to edit it. Fill in the fields under the Frequency tab:

  Note If frequency conversion is not enabled, use the AC simulation component to specify the simulation frequencies-don't use the frequency parameters on the sources. If frequency conversion is enabled, use the sources to specify frequencies; do not use the AC simulation component's frequency entries.

  • Select the sweep type. For a single point, enter the frequency. For a linear or logarithmic sweep, elect to define the sweep with start/stop or center/span values.
• To calculate noise, select the Noise tab and enable Calculate noise. You select a node for noise calculations from the Edit list, then click Add. Use the Mode list to sort the noise contributed by individual noise sources by name or value.
• You can enable frequency conversion, which is useful when analyzing circuits with standard (not user-defined) behavioral mixer models. For more information on this option, refer to Enabling Frequency Conversion.
• You can perform budget calculations as part of the simulation. For more information on budget analyses, see Using Circuit Simulators for RF System Analysis.

For details about each field, click Help from the open dialog box.