Amplifiers

Depending on their application, amplifiers can have very different specifications. Low-noise stages found in receivers are hardly comparable to power stages feeding a transmitting antenna. However, certain characteristics such as linearity and power consumption are, to varying degrees, common to most amplifiers.

In this article, the focus is on "radio-frequency" or "microwave" amplifiers.

In the first part, the main concepts relating to amplifiers (different gains, mismatching, noise figure, intermodulation products, etc.) will be explained. The measurement of some of these characteristics will be briefly mentioned.

In the second part, we'll discuss the various possible structures of high-level amplifiers in terms of efficiency, linearity and frequency band constraints.

Readers are referred to references [1] to [3].