Editing Common base (section)

== Applications ==
This arrangement is not very common in low-frequency discrete circuits, where it is usually employed for amplifiers that require an unusually low [[input impedance]], for example to act as a [[preamplifier]] for moving-coil [[microphone]]s.
However, it is popular in integrated circuits and in high-frequency amplifiers, for example for [[VHF]] and [[Ultra high frequency|UHF]], because its input capacitance does not suffer from the [[Miller effect]], which degrades the bandwidth of the [[common-emitter]] configuration, and because of the relatively high isolation between the input and output. This high isolation means that there is little feedback from the output back to the input, leading to high stability.

This configuration is also useful as a current buffer, since it has a current gain of approximately [[unity (mathematics)|unity]] (see formulae below). Often a common base is used in this manner, preceded by a common-emitter stage. The combination of these two form the [[cascode]] configuration, which possesses several of the benefits of each configuration, such as high input impedance and isolation.