What device is typically used as a stable reference voltage in a linear voltage regulator?

A Zener diode is typically used as a stable reference voltage in a linear voltage regulator because of its ability to maintain a constant voltage across it, regardless of changes in current. When reverse-biased, a Zener diode operates in its breakdown region, allowing it to provide a consistent reference voltage that is unaffected by fluctuations in load current or input voltage variations. This property is crucial in voltage regulation applications, where a stable output voltage is necessary for the proper operation of electronic circuits.

Transistors, while important in amplification and switching applications, do not inherently provide a stable reference voltage. Capacitors are used mainly for filtering and energy storage, and inductors are utilized for energy storage in magnetic fields, neither of which serve the purpose of providing a stable voltage reference for regulation. This makes the Zener diode the most suitable choice for maintaining a constant voltage in linear voltage regulator designs.