Diode vs. Transistor: Key Differences Explained

This article clarifies the fundamental distinctions between diodes and transistors.

Diode

A diode is a two-terminal electronic device consisting of an anode and a cathode. The voltage characteristics of various diode types dictate their specific applications.

Common diode types include:

• GUNN
• Varactor
• Tunnel
• PIN
• Zener
• Schottky
• Impatt
• Trapatt
• Baritt

Diode Forward Voltage

This refers to the voltage across the diode’s electrodes when current is flowing. The current increases exponentially with the voltage. This results in a relatively constant voltage over a typical range of currents. Diodes typically exhibit a voltage of 0 to 7 volts at 10 mA, making them highly useful. A diode can serve as a voltage reference when configured to provide a reference voltage equal to the forward voltage across its terminals.

Transistor

A transistor is a solid-state counterpart to a triode vacuum tube.

Different types of transistors exist, including:

• BJT (Bipolar Junction Transistor)
• FET (Field-Effect Transistor)
• MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor)

BJTs are current-controlled devices, providing amplification or gain to an input signal. The common terminals in a BJT are the Collector, Emitter, and Base. Furthermore, BJTs come in two configurations: PNP and NPN. Silicon and germanium are commonly used semiconductor materials in transistor construction.

FETs are voltage-controlled devices with Source, Gate, and Drain terminals.