Power Amplifier 1dB Comp. - RF Cafe Forums
Post subject: Power Amplifier 1dB comp.
Wed Feb 02, 2005 5:25 pm
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 9:02 pm
One reason could be the spec sheet overstates the P1dB of the device.
But lets wait for a possible reason.
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.
postPosted: Thu Feb 03, 2005 9:44 am
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 ?
1. What is the part vendor/
2. What is the bias voltage you are using?
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
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.
it helps. :D
Unread postPosted: Tue Mar 15, 2005 10:02 am
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).