Which amplifier typically has the lowest voltage gain among the common configurations?

The common collector amplifier, often referred to as an emitter follower, is known for having the lowest voltage gain among the common amplifier configurations. This is due to its design and function.

In a common collector configuration, the output is taken from the emitter, while the input is applied to the base. The primary purpose of this configuration is to provide a high current gain rather than a high voltage gain. The voltage gain in this case is typically slightly less than 1, meaning the output voltage closely follows the input voltage, but with less ability to amplify the voltage level.

The common collector amplifier is also valuable for impedance matching, as it has a high input impedance and a low output impedance. This makes it suitable for interfacing different circuit stages, especially where you want to connect a high-impedance source to a low-impedance load.

In contrast, configurations like the common emitter and common base amplifier generally offer higher voltage gains, with the common emitter providing the highest gain among the configurations listed. The common gate amplifier, which is a variation used primarily in RF applications, also provides significant voltage gain. Therefore, the characteristics and purpose of the common collector amplifier clearly establish it as the configuration with the lowest voltage gain.