Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
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Nonlinear wideband (power) amplifier - RF Cafe Forums
RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media
platforms dominating public commenting venues. RF Cafe Forums began sometime around
August of 2003 and was quite well-attended for many years. By 2010, Facebook and
Twitter were overwhelmingly dominating online personal interaction, and RF Cafe
Forums activity dropped off precipitously. If the folks at
phpBB would release a version with integrated
sign-in from the major social media platforms, I would resurrect the RF Cafe Forums,
but until then it is probably not worth the effort. Regardless, there are still
lots of great posts in the archive that ware worth looking at.
Below are the old forum threads, including responses to the original posts.
|-- Amateur Radio
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Test & Measurement
Post subject: Nonlinear wideband (power) amplifier Posted:
Tue May 16, 2006 5:21 am
Joined: Tue Dec 13,
2005 2:42 am
Location: Czech Rep.
I just want to ask you.
I would like to build a wideband 'power'
amplifier working let's say in C Class. (I'm speaking about 150-450MHz
band approximately, 0.5-1W out.)
Does the nonlinear wideband
amplifier even exists? ...Because I haven't found anything about it.
Do you have some design recommendation?
Thank you for help,
Post subject: Broadband Class
C amplifierPosted: Tue May 16, 2006 6:33 pm
Joined: Wed Feb 22, 2006 3:51 pm
C amplifiers are unfortunately inherently not wideband. Here's why
Class C amplifiers are defined by having a conduction angle of less
than 180 degrees. This results in a pulse of current being applied to
the output network, which resonates at the operating frequency. This
resonance reduces the harmonics which are necessarily generated with
less than 180 degrees conduction angle. The Q may vary, but the resonance
is critical to the proper operation of the circuit.
current pulse is not symmetrical, both even and odd harmonics are generated.
So in your specifications, a 150 MHz input signal would result in 300
and 450 MHz spurious signals, which would not be filtered out - not