| ??? 05/25/07 06:10 Read: times |
#139808 - not getting any output Responding to: ???'s previous message |
Hi Kai,
My problem is that I'm not getting any power output. I've got a board that doesn't have a PA (outputs 0dBm) and I'm getting much more power out than with the PA. I think the problem might be in the reference schematic of the Sige 2423L which I copied directly. They show a parallel LC from Vcc to the output of the PA. The resonant frequency of the LC given their component selection is about 7.1GHz. In every PA circuit I've dealt with you always tune this LC resonant frequency to the frequency of opperation (2.4GHz in my case and in the reference design case). They're calling that LC a 3rd harmonic shunt, but in my mind it's a fundamental shunt (provides a nice path to ground via a 10 pF cap that sits from Vcc to gnd) and a 3rd harmonic pass - when the impedance of the LC is maximized all the RF energy will go to the antenna. In this case that means 7.1 GHz goes to the antenna. I'm fairly confident that the problem is in the output matching network of the PA and am wondering if anyone can enlighten as to the recommended component selection for the LC. Thanks, D |
| Topic | Author | Date |
| RF forum/question? | 01/01/70 00:00 | |
| Physician's Assistant? | 01/01/70 00:00 | |
| Daddy? | 01/01/70 00:00 | |
| Power Amp | 01/01/70 00:00 | |
| this is not a RF forum | 01/01/70 00:00 | |
| Power Amplifier | 01/01/70 00:00 | |
| my intent was not ... | 01/01/70 00:00 | |
| Power Attenuator | 01/01/70 00:00 | |
| What is your problem? | 01/01/70 00:00 | |
| not getting any output | 01/01/70 00:00 | |
| Don't forget C2, C12 and the stray capacitances | 01/01/70 00:00 | |
| a little more.. | 01/01/70 00:00 | |
| Don't take the values too seriously,... | 01/01/70 00:00 | |
| fair enough | 01/01/70 00:00 | |
Electrodynamics instead of electrostatics... | 01/01/70 00:00 |