"Predefined [[Tests]]", on the other hand, are run with some advance planning and preset simulation [[parameters]]. You can run [[tests]] to analyze your circuit in time and frequency domains and characterize its DC bias (operating point), transient and steady-state AC responses, noise performance, network [[parameters]], etc. The output results of [[RF.Spice A/D]] [[tests]] are displayed on graphs or tabulated in tables.
== Working with Two Simulation Engines ==
[[RF.Spice A/D]] has two distinct and independent simulation engines: the mixed-mode simulator and the event-driven digital simulator. Each of these two simulators has its own schematic mode and both are based on the Berkeley Spice and XSpice engine codes. The mixed-mode simulator simulates analog, RF and mixed analog/digital circuits. If your circuit is pure analog or RF or contains both analog and digital parts, then the mixed-mode schematic and simulator are used. If your circuit is pure digital, then the digital schematic and simulator are evoked, which allow for interactive inputs and outputs.