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Stability of a balanced amplifier - RF Cafe Forums
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ljoseph
Post subject: Stability of a balanced amplifier Posted:
Sun May 04, 2008 8:08 am
Captain
Joined: Tue Sep
04, 2007 7:54 am
Posts: 13
Location: Dallas
I have a balanced
amplifier with Avago's ATF58143 pHEMT. The balanced amplifier is unconditionally
stable, but the the individual stages are not. Is this OK?. Elsewhere
I read that we need not care stability of Individual stages...just make
the total balanced amplifier stable.
Please let me know your thoughts
on this.
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IR
Post subject: Posted: Wed May
07, 2008 3:57 pm
Site Admin
Joined: Mon Jun 27, 2005
2:02 pm
Posts: 373
Location: Germany
Hello ljoseph,
In principle you should not be concerned about each stage. One of
the advantages of balanced amplifier is the improved impedance matching
both at the input and at the output of each stage (Due to the quadrature
couplers), this improves the stability of each of the amplifiers. When
each amplifier works as a stand-alone unit, it is therefore much less
stable due to degraded matching and is prone to oscillations.
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Tony Kurlovich
Post subject: Posted: Fri May
16, 2008 5:37 pm
Captain
Joined: Thu Oct 19, 2006
6:02 pm
Posts: 7
In a balanced amplifier, there is the risk of
common mode oscillation in an apparently stable device.
Posted 11/12/2012
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