A fixed output voltage of a preset magnitude is generated by a voltage Regulator that remains constant irrespective of changes to its load conditions or input voltage. Switching and linear are two types of voltage regulators.

An active pass device controlled by a high gain differential amplifier is employed by a linear regulator. With a precise reference voltage, it compares the output voltage, and to maintain a constant output voltage, it adjusts the pass device.

To a circuit that controls the power switch on and off times, the filtered power switch output voltage is fed back so that regardless of load current or input voltage changes, the output voltage remains constant.