What is the most frequently used arrangement in practical amplifier circuits?

The most frequently used arrangement in practical amplifier circuits is the common-emitter configuration. This configuration is favored for several reasons, primarily its ability to provide a significant voltage gain, which is essential for most amplification applications.

In a common-emitter amplifier, the input signal is applied between the base and the emitter of the transistor, while the output is taken from the collector and the emitter. This setup allows for high gain due to the transistor's ability to modulate the collector current significantly with small changes in base current. Consequently, the output voltage variation is much larger than the input, resulting in amplification.

Additionally, common-emitter amplifiers provide phase inversion, which can be advantageous in certain signal processing applications. The configuration also has a relatively high input impedance and a low output impedance, making it versatile for interfacing with different stages in an electronic circuit.

Overall, the common-emitter configuration strikes a good balance between gain, frequency response, and impedance matching, making it the cornerstone of many analog circuits, including audio amplifiers and radio frequency amplifiers.