A voltage regulator that is placed close to the device or devices for which it is powering is commonly referred to as a point of load (POL) regulator. A POL regulator often receives its input from a voltage bus contained on the PCB. The amount of current an IC consumes when it is not sourcing current and its inputs are not cycling is defined as quiescent current. Efficiency is defined as the ratio of power into a regulator circuit to the output power delivered by the regulator. Power input includes quiescent currents, losses due to parasitic components and power delivered to the load. Equivalent series resistance is the resistive component of the capacitors used in a regulator circuit. Attention needs to be paid to the ESR of the capacitors of the output. The loop is defined as all the elements affecting the output and stability of a regulator. This includes such blocks as the power stage, error amplifier, modulator, and compensation circuits.