parallel feed back resistor - RF Cafe Forums
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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