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 etc.
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,
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
3-P1dB is 5W
4-Biased at 24V,800mA