Post subject: Parasitic oscillations Posted: Tue Jul 26, 2005
Could someone suggest a couple of good references
on low frequency parasitic oscillations in microwave amplifiers?
Post subject: Posted: Tue Jul 26, 2005 7:58
Joined: Mon Jun 27, 2005 2:02 pm
Please try the following:
http://www.semiconductors.philips.com/a ... /LNA97.pdf
Post subject: ThnxPosted: Tue Jul 26, 2005
Thank you very much for the reference. I will
have a re-look at the biasing circuitry and the bypass capacitors in
my circuit. From a practical standpoint, how would one determine (when
testing the amplifier) if low frequency products were modulating the
Post subject: Posted:
Tue Jul 26, 2005 9:25 am
If you know the bandwidth
of your input modulated signal you can see if the voltage on various
points (Base, collector) on the amplifier's circuit has AC components
(With high-speed oscilloscope or with spectrum analyzer don't forget
to use DC block for this measurement) if you see these components at
these points, you can estimate by their magnitude if your bypassing
is adequate or not.
Alternatively, you can inject 2 input CW
signals with known offset between them and do this measurement.
Should you need more information, please let me know.