What Is Leakage Current?

Leakage current is the unintended loss of electrical current or electrons. The term is often applied to computer microprocessors, which are the chips that perform calculations and process data. In fact, leakage is a problem that inhibits faster advancements in computer performance. The term also applies to electronics and consumer electronics devices.

Semiconductors make use of millions of transistors to perform calculations and store data in computer microprocessors. Transistors are devices used to amplify and switch electronic signals. Leakage current in semiconductors occurs at the transistor level. As semiconductor manufacturers continue to make transistors smaller to squeeze more onto a chip, leakage current problems increase. Smaller transistors have thinner insulating layers, causing more leakage current.

Leakage in transistors causes semiconductors to require more power to operate, as they must replace the current lost to leakage. The leakage current also generates heat as it leaks away, which leads to degraded performance for the semiconductor. When the heat from leakage is combined with the heat generated by the semiconductor's normal operation, it can become a significant problem. Excessive heat can eventually cause circuit failure. Designers may take a number of different approaches to reduce the amount of leakage.

In electronics, leakage current refers to the unintended loss of energy from a capacitor. A capacitor is a passive electric component that can create an electrical field and that can store energy. The capacitor discharges slowly at all times as a little bit of electrical current passes through the capacitor's electronic components, including transistors and diodes, at all times. Even when the capacitor is turned off, the small amount of current is passing through, which causes the problem. Leakage current in electronics also can refer to the current that flows through a ground conductor.

For consumer electronics devices, leakage current can refer to the device pulling electrical current, even when powered down. Some devices, such as cell phones, will pull a little bit of current, even when the battery is already fully charged. Some other battery-charged devices might pull a little bit of power, even when in sleep mode, which also is referred to as leakage current. This is one reason why experts recommend unplugging cell phone chargers and other devices when they are not in use; over time, this current leakage can add up and raise energy bills.