Power Amplifier 1dB comp. - RF Cafe Forums
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Post subject: Power Amplifier 1dB comp.
Unread postPosted: Wed Feb 02, 2005 5:25 pm
Joined: Wed Feb 02, 2005 5:18 pm
I need to know what
might be the reason to the fact that a PA do not deliver the full output power that specify in tech.
specifications allthough that it's very well matched ?
In a different words, what is the part that responsible
to the 1db comp. point in class AB PA ?
Unread postPosted: Thu Feb 03, 2005 9:38 am
Joined: Thu Nov 04, 2004
One reason could be the spec sheet overstates the P1dB of the device. But lets wait for a
Also, when a datasheet says the device operating point as 0.5Idss, does it imply just DC
current due to bias or includes any DC component generated by the PA itself from the harmonics?
Post subject: Re: Power Amplifier 1dB comp.
Unread postPosted: Thu Feb 03, 2005 9:44
I need to know what might be the reason to the fact that a PA do not
deliver the full output power that specify in tech. specifications allthough that it's very well matched ?
different words, what is the part that responsible to the 1db comp. point in class AB PA ?
1. What is the part vendor/ model number?
2. What is the bias voltage you are using?
3. Are you sure
your test setup isn't compressing (or is not calibrated properly), and not the amp?
Unread postPosted: Tue Mar 15, 2005 4:50 am
I'd like to share some views
on this matter. Maybe I have some suggestions on having higher P1dB, pls check whether the amplifier is biased at
correct biasing point. I mean, if the supply voltage or current is too low, it can't drive power amplifier till
the expected levels.
And also you can try to do some tuning in output matching to get higher saturation
power. Usually at higher saturation power, P1dB is expected to be higher.
and I agree with a fellow that
said, the calibration system measurement necessary to re-check, be careful on the power meter offset setting.
Hope it helps. :D
Unread postPosted: Tue Mar 15, 2005
The ability to deliver high output power is considered by 2 factors: The bias point
and output matching. There is more than only possible way to match the output of the device: Could be for output
power, high linearity etc. You should verify that the device is biaesd correctly, and matched to the condition of
maximal output power (i.e conjugate match).