Chapter 2 - DC Bias Point Analysis

Abstract

When a battery or a power supply is connected to a circuit, the circuit voltages and currents effectively settle down to a DC steady-state condition. This is also known as the operating point or bias point of a circuit under steady-state conditions. In PSpice, the bias point analysis calculates the node voltages and currents through the devices in the circuit. Bias point analysis also takes into account any voltage sources applied to the circuit and any initial conditions set on devices or nodes in the circuit. With the bias point enabled, the output file provides a list of the entire analog and digital node voltages, the currents, and total power of all voltage sources in the circuit, and a list of small signal parameters for all devices in the circuit. The circuit diagram drawn in Capture is represented as a netlist of all the components and their respective connections to other components. This netlist is automatically generated when users run the simulation, and can be seen in the Outputs folder in the Project Manager. After a simulation is run, the bias voltage, current, and power values can be displayed on the schematic. Users can save and reuse the bias point data from a simulation, which is useful if a number of simulations have to be run on a large circuit that has a long simulation runtime. Saved bias point analysis data are loaded by selecting the Load Bias Point option in the simulation profile.