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发表于 2008-9-13 09:13:00
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CHAPTER 2
POWER AMPLIFIER
2.0 Introduction
The main characteristics of an amplifier are Linearity, efficiency, output power, and
signal gain. In general, there is a trade off between these characteristics. For example,
improving amplifier’s linearity will degrade its efficiency. Therefore knowing the importance
degree of each one of these characteristics is an essential step in designing an Amplifier. This
can be jugged based on the application. As an example high output power Amplifier is used
in the transmitter side of a transceiver, whereas high linear amplifier used in the receiver side.
An amplifier is said to be linear if it preserves the details of the signal waveform, that
is to say,
(2.1)
where, Vi and Vo are the input and output signals respectively, and A is a constant gain
representing the amplifier gain. But if the relationship between Vi and Vo contains the higher
power of Vi, then the amplifier produces nonlinear distortion.
The amplifier’s efficiency is a measure of its ability to convert the dc power of the
supply into the signal power delivered to the load. The definition of the efficiency can be
represented in an equation form as....................... |
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