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Audio amplifier design trivial?
(Bob-Stanton) wrote in message om...
"Robert Morein" wrote in message
I did some Google reading, and it appears that commercial CATV amplifier is
a very demanding case. However, design of a CATV amplifier has different
problems; it is not simply the case that it is more complex.
Were it not for the cascade requirement, one could make the case that the
audio amplifier is a greater challenge. In fact, I am not aware of any audio
amplifier ever produced that could meet the "analogous" CATV specs.
For an uncascaded RF amplifier, some characteristics of the problem are
relaxed compared to the audio amp.
That's right, they have a different set of problems. There is a hidden
complexity in RF circuits. A componet at audio frequencies is simple
single impedance. At RF a resistor is a network of three componets
(resistance, lead inductance, body capacitance). All these....
parasitic reactances make the resistor a small, two terminal network,
whos impedance changes with frequency.
A 100 pf capacitor, with 0.5 inch leads, becomes an inductor above 200
MHz.
Fields couple RF stages together and give strange unpredictable
results. There is more complexity in an RF design than is apparent
from the schemetic.
Bob Stanton
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