Programming instructions

Opamp
 National Instruments Corporation 5-3 Multisim Component Reference Guide
5.1.3 Opamp: Simulation Models
Several types of simulation models are included in Multisim. The following model levels are
used to distinguish between the various models:
• Virtual 3T — this is the simplest model with the opamp modeled as a gain block with a
differential input and a single ended output.
• Virtual 5T — this is a more complex model in which the supply voltages are included in
the simulation.
• Real — these are models of increasing complexity where additional control pins are
supported.
5.1.3.1 Virtual 3-Terminal Opamp
This is the simplest simulation model.
The modeled opamp parameters are:
• open loop gain
• input resistance
• output resistance
• negative voltage swing
• positive voltage swing
• input offset voltage
•slew rate
• unity-gain bandwidth
• input bias current
• input offset current
• compensation capacitance
The opamp is modeled by distributing the open-loop voltage gain,
A, across three stages. The
first and second stages model the first and second poles of the opamp, and the third stage
models the output impedance.
ComponentRef.book Page 3 Thursday, December 7, 2006 10:12 AM