A Bode Diagram to Display a Control Loop (Download)
A power supply is supposed to generate a stable, regulated output voltage. To make sure it does, the output voltage can be measured at different load currents and different input voltages. Then, the results would be looked at to determine whether the output voltage is within a desired tolerance range.
Such a basic check is an important part of designing a power supply, but it only shows part of the truth. If the load current (or supply voltage) changes during operation, the voltage generated should be maintained as well as possible. By displaying the transfer function of a power-supply loop, a Bode plot can fill in the gaps. While there are load-transient tests in the time domain, the results don’t show other important information that’s provided by a Bode plot.
