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From: Paul Burridge
Subject: Re: Help! Diode biasing of Class B amplifiers
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Date: Sat, 05 Oct 2002 18:26:41 +0100
NNTP-Posting-Date: Sat, 05 Oct 2002 18:26:28 BDST
Organization: Virgin Net Usenet Service
On Sat, 05 Oct 2002 14:32:11 GMT, Chuck Simmons
>You need to look at this differently. Keep in mind that there is a bias
>current through the diodes.
Okay. So is the core of the solution that the level of this forward
bias current is chosen so that even at 'peak opposing-bias input
voltage swing' there will still be just enough flowing to prevent the
devices from going into cut-off? The diagrams I've seen will produce
only about 5mA of bias current under quiescent conditions; it doesn't
seem like enough to prevent cut-off at driver voltage output levels?
[confusing explanation snipped]
>Sorry, that is really confusing.
I'll say! :-) Any clarification from yourself or anyone reading this
would be welcome.
>For that type of circuit to work well, there is usually a boost voltage
>for the diode bias.
You mean a decent *current* source, surely? Something that can cope
with extremes of input signal swing in a way that resistors can't
without wasting too much current at other points in the cycle?
In AC applications, the output can be rectified and
>filtered to produce the needed boost. Drat! Even more confusing.
You mean "bootstrapping"?
Noverint universi per presentes et futuri...
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