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楼主 |
发表于 2009-12-5 09:32:06
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初次发帖,希望大家多多关照。我发下这个的介绍
1. INTRODUCTION
Some graphic and numerical methods of impedance
matching will be reviewed here. The examples given will refer
to high frequency power amplifiers.
Although matching networks normally take the form of
filters and therefore are also useful to provide frequency
discrimination, this aspect will only be considered as a
corollary of the matching circuit.
Matching is necessary for the best possible energy
transfer from stage to stage. In RF-power transistors the
input impedance is of low value, decreasing as the power
increases, or as the chip size becomes larger. This
impedance must be matched either to a generator — of
generally 50 ohms internal impedance — or to a preceding
stage. Impedance transformation ratios of 10 or even 20 are
not rare. Interstage matching has to be made between two
complex impedances, which makes the design still more
difficult, especially if matching must be accomplished over
a wide frequency band. |
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