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Power Amplifier 1dB comp. - RF Cafe Forums

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Below are all of the forum threads, including all the responses to the original posts.


PILOT005
Post subject: Power Amplifier 1dB comp.
Unread postPosted: Wed Feb 02, 2005 5:25 pm
Offline
Lieutenant

Joined: Wed Feb 02, 2005 5:18 pm
Posts: 1
Hello,

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 ?

Thanks.


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np101010
Post subject:
Unread postPosted: Thu Feb 03, 2005 9:38 am
Offline
Captain

Joined: Thu Nov 04, 2004 9:02 pm
Posts: 7
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?


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Guest
Post subject: Re: Power Amplifier 1dB comp.
Unread postPosted: Thu Feb 03, 2005 9:44 am

PILOT005 wrote:
Hello,

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 ?

Thanks.


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?


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Jeanalmira
Post subject:
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


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Itay
Post subject:
Unread postPosted: Tue Mar 15, 2005 10:02 am

Hello,

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).

Itay







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