在电子学中，共集极（英语：Common collector）放大器是双极性晶体管（bipolar junction transistor (BJT)）放大器电路的三种基本组成方式之一（另外两种为共射极和共基极），通常被用在电压缓冲器中。在这种电路接法里，晶体管的基极充当输入端，射极则充当输出端，集电极作为二者的公共端（例如接地或者连接到一个电源），“共集极”因此得名。在场效应管中，类似的概念称作共漏极。

In electronics, a common collector amplifier (also known as an emitter follower) is one of three basic single-stage bipolar junction transistor (BJT) amplifier topologies, typically used as a voltage buffer.

In this circuit the base terminal of the transistor serves as the input, the emitter is the output, and the collector is common to both (for example, it may be tied to ground reference or a power supply rail), hence its name. The analogous field-effect transistor circuit is the common drain amplifier and the analogous tube circuit is the cathode follower.