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
while tying up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
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My Hobby Website:
parallel feed back resistor - 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
Gripes & Humor
-- CAE, CAD, &
Test & Measurement
Post subject: parallel feed back resistor Posted: Tue Aug
23, 2005 3:35 am
Can any one explain how do we determine
the safe value of parallel feed back resistor being used to level the
gain and stabilize the device as well. My concern is the heat dissipation
due to Rf energy. I am using it for various RF power out puts eg, 5W,10W
Post subject: Parallel Feedback
ResistorPosted: Tue Aug 23, 2005 7:19 pm
One of the replies you
hear a lot on this site is "what are the details of your application".
The reason is that there are no totally general formulas or rules for
anything - there are always trade-offs that get made differently, depending
on the parameters of the situation. Feedback techniques appropriate
for LNAs are not necessarily the techniques you'd use for an HPA.
Normally, you don't want to burn up too much power in resistors,
regardless of where they are. If it's RF power you're burning up, that's
pretty costly stuff!
So the questions are,
1. What frequency
range are you talking about?
2. What kind of circuit are you talking
about? That's important because if you need to stabilize a circuit,
you already have feedback - and you've got to know the nature, amount,
and effects of that feedback.
3. Are there any other objectives?
Linearity: harmonic distortion, IMD, Third-order intercept, etc. Efficiency?
Post subject: Posted:
Wed Aug 24, 2005 3:29 am
2-Single ended, Class A
3-TOI 10dB higher than P1dB
3-P1dB is 5W
4-Biased at 24V,800mA