Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would
be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate
that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views.
It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if
you would like to post something on RF Cafe's
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: Power Amplifier 1dB comp.
Wed Feb 02, 2005 5:25 pm
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 ?
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/ 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
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 10:02 am
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).