A question about matching 1GHZ power amplifier,help ME plz!

[ChaoFan]

Hi,ALL

The picture below is a matching circuit of MRF9045 at 1GHZ, But now I need

to use MRF9045 working at 800MHZ, so I need to match it by myself.

The question is how to match it, if I know the input and output impedence?

Just use the Smith chart to do the match? Will the copper foil around the

microsthip have effect on the signal in the microsthip? I am so puzzled about this!

You konw, in the model of microtrip, there is no any copper foil around the

microtrip!

Maybe I am wrong. But plz tell me why the test circuit use this matching

circuit!

Help me! Thank you!

 

[Element_115]

Re: A question about matching 1GHZ power amplifier,help ME p

It depends on how you want to match it.

1) are you going to re-spin the board?

2) Just try to tune it low in Freq?


If you take route #1, Use the I/P & O/P Impendence from the spec/data sheet
and do the conjugate match. Since it's a PA impedance matching is the way to
go. Also leave/make room to tune, and remember that going lower in Freq means
that the line length will get a little longer!


If you go route #2, Slowly slide those cap back and forth to see where the "Sweet
Spot" is . Add copper tabs, and change the inductor and cap values.
And Do all these suggestions slowly and in small value changes, because you could
make the Amp unstable and blow the device!

Hope this helps

 

[ChaoFan]

Thank you,Element_115.
But I need more advice!
who can help me?