Performing a Large-Signal S-Parameter Simulation

Start by creating your design, then add current probes and identify the nodes from which you want to collect data. For a successful analysis:

• Apply ports to all inputs and outputs. Use a P_1Tone or P_nTone power source to drive a port. Terminate other ports using port-impedance terminations (Term). Verify impedance.

  Note The power level at a passive port (Term) will be calculated by turning on power sources and measuring the power at the port; this value will be used to drive the port.

• Check the Num field for each port. The S-parameter port numbers are derived from these fields. For a 2-port circuit, you want the input labeled as Num = 1 and the output as Num = 2.
• In circuits with mixers, use a voltage source for the LO, not a power source. This prevents the LO input from being recognized as a port and consequently having the S-parameters calculated with respect to it.
• Add the LSSP control element to the schematic, then double-click to edit its parameters in the fields under the Freq and Ports tabs:
  • For Freq, set the fundamental frequency and order.
  • For Ports, set the port frequency for each port. S-parameters will be measured at this frequency. Port frequency can be the input frequency or a harmonic.
  • For choosing a matrix solver, the Auto Select mode is the default and recommended choice. For instructions about using this option, see Selecting a Solver in the Harmonic Balance Simulation documentation.
• You can use previous simulation solutions to speed up the simulation process. For more information, see Reusing Simulation Solutions in the Harmonic Balance Simulation documentation.

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