MOSFET Switch and MOSFET Amplifier | MOSFET Application note

This MOSFET application note covers basic description on MOSFET Switch and MOSFET Amplifier. The circuit diagram is mentioned.

MOSFET switch

The figure-1 depicts Enhancement mode type N-channel MOSFET device. As shown the MOSFET is switched ON when positive voltage is applied as VGS. This will drive the LAMP connected on Drain terminal to be powered ON.

When zero voltage is applied to the device at VGS, it will be powered OFF. Hence Lamp will be powered OFF at this stage.

MOSFET amplifier

In many applications MOSFET is used as small signal linear amplifier. Figure-2 depicts MOSFET used as amplifier.

Typically, in the amplifier circuits, FETs work in the saturation region. In this region, current does not depend on drain voltage. Current is the function of the Gate voltage only. In MOSFET amplifiers, the operating point is normally in the saturation region.

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