The Gate Voltage (Vg) is the voltage applied to the gate terminal of a transistor, particularly in the context of metal-oxide-semiconductor field-effect transistors (MOSFETs). The gate voltage controls the flow of current between the source and drain terminals in a MOSFET.

In an n-channel MOSFET, applying a positive gate voltage relative to the source terminal creates an electric field that attracts electrons from the source to the channel region under the gate. This process forms an inversion layer, allowing current to flow from the source to the drain. In a p-channel MOSFET, a negative gate voltage is applied to create an inversion layer for the flow of holes.

The gate voltage is a critical parameter as it determines the state of the transistor—whether it is in an off state, where little to no current flows, or in an on state, where current can flow between the source and drain terminals. The relationship between the gate voltage and the current flowing through the transistor is described by the transistor’s characteristic curves, often shown in the form of transfer characteristics or output characteristics.

Control of the gate voltage is essential in electronic circuits, as it allows for the amplification and modulation of signals, making MOSFETs and similar devices fundamental components in integrated circuits and electronic systems.

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