Discussion Overview
The discussion revolves around plotting the Voltage Transfer Characteristic (VTC) of a BiCMOS logic inverter circuit using OrCAD Capture Lite. Participants explore various methods and configurations for achieving this, including simulation settings and circuit component arrangements.
Discussion Character
- Technical explanation
- Debate/contested
- Mathematical reasoning
Main Points Raised
- One participant seeks assistance with plotting the VTC and mentions difficulties with dividing output and input signals in OrCAD Capture Lite.
- Another participant inquires whether the original poster is using actual PSpice code or the OrCAD GUI.
- A suggestion is made to configure the simulation as a DC or parametric sweep and to add a trace of the output voltage divided by the input voltage after running the simulation.
- There is a question about whether a single output variable can be used or if an operator is needed to divide the two signals.
- A participant offers a detailed explanation of setting up the simulation profile, including the need to sweep a voltage source and the configuration of the input node.
- After attempting the suggested method, the original poster reports that the plot does not appear correct, indicating potential issues with the circuit itself.
- Another participant asks for details about the type of circuit being modeled and suggests posting screenshots of the circuit and results.
- The original poster shares links to images of the circuit and output plots, asserting that the circuit is correct as per the lab manual.
- One participant identifies a missing resistor in the circuit and suggests that the issue may still lie with the circuit or components used.
- Another participant expresses uncertainty about the circuit's accuracy and questions whether the model components are comparable to real-world counterparts.
- A suggestion is made to define the output node as a net alias and to check the orientation of the p-MOS FET in the circuit.
- There is a discussion about the characteristics of the VTC produced by OrCAD and the potential need to use the D() function for more accurate derivative calculations.
Areas of Agreement / Disagreement
Participants express various viewpoints on the configuration and accuracy of the circuit, with no consensus reached on the source of the plotting issues. Multiple competing views remain regarding the effectiveness of the simulation setup and the characteristics of the VTC.
Contextual Notes
Participants note potential limitations related to the accuracy of model components and the configuration of circuit junctions, as well as the need for further verification of the circuit's correctness.
