TABLE OF CONTENTS Amplifiers are components that many people do not really regard as components. They somewhat elevate them above components because they seem to be so much more important than something like an attenuator. Actually, all of the components that we have covered, and will cover, are equally important. The amplifier is just one more with which to be come familiar.
To understand the amplifier and how it is used for RF and microwave applications, we must first define certain terms for it, just as we have done with all of the previous components.
The first term to be defined is amplification. If you have been to a rock concert lately, you can fully understand this term. If you haven't been to a concert, it is the increase in the level of a signal to produce the required amount (voltage or power) at the output of a system or section of a system. This increase in signal is accomplished by an active device (that is, a device which requires a dc voltage for its operation) that takes a small input signal and produces a larger output signal. This relationship is shown in Figure 4.55. You will notice from the figure that we have used both voltage and power to indicate input and output signals. This gives you flexibility in dealing with a variety of amplifiers. Generally, in RF and microwave applications, you will find it much more convenient to deal only with power. These levels are easier to measure...
