How many basic configurations may a transistor be connected in?

Transistors can be connected in three basic configurations: common emitter, common base, and common collector. Each configuration serves a specific purpose and has distinct characteristics in terms of voltage and current amplification, input and output impedance, and phase shift.

In the common emitter configuration, the input is applied between the base and emitter, while the output is taken between the collector and emitter. This setup is widely used due to its ability to provide significant voltage and current gain.

The common base configuration, on the other hand, has the input connected to the emitter and the output taken from the collector. It is less commonly used but offers a very high frequency response and is often utilized in RF applications.

Finally, the common collector configuration, also known as an emitter follower, has the input connected to the base and output from the emitter. This configuration does not provide voltage gain but is useful for impedance matching because it has a high input impedance and low output impedance.

Understanding these three configurations helps in circuit design and analysis, as each has unique advantages suitable for particular applications.