In contrast to the linear regulator, the control device in the switching regulator is either fully on or fully off. As a result, its power dissipation tends to be reduced. For best performance, fast control devices are needed. The control device is driven by a pulse-width modulator. The output of this modulator is a rectangular pulse whose duty cycle is proportional to the load-current demand. As the control device produces current pulses instead of a constant current, some means of smoothing the pulses is necessary. This function is performed by an $$LC$$ filter. The main advantage of the switching regulator is its high efficiency. On the down side, switching regulators are somewhat more difficult to design, do not respond as fast to transient load conditions, and tend to radiate high frequency interference.