Yhteisemitteri

Yhteisemitteri is a term in Finnish that translates to "common emitter" in English. It refers to a fundamental configuration of a bipolar junction transistor (BJT) amplifier. In a common emitter configuration, the input signal is applied to the base, the output signal is taken from the collector, and the emitter terminal is common to both the input and output circuits, often connected to ground or a fixed bias voltage.

This amplifier configuration is widely used due to its ability to provide significant voltage and current gain, making it a versatile building block in electronic circuits. The common emitter amplifier typically exhibits a phase inversion between the input and output signals, meaning a positive-going input voltage results in a negative-going output voltage, and vice versa. The output impedance of a common emitter amplifier is generally moderate, while its input impedance is relatively low.

The operating characteristics of a common emitter amplifier are influenced by factors such as the transistor's parameters, biasing conditions, and the values of external components like resistors and capacitors. It is a staple in audio amplifiers, radio frequency circuits, and various switching applications. Understanding the common emitter configuration is crucial for anyone studying analog electronics and transistor circuit design.