# OIP3-estimatedP1dB - RF Cafe Forums

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Jeanalmira

Post subject: OIP3-estimatedP1dB

Unread postPosted: Wed May 04, 2005 9:45 pm

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Hi all:

I have questions regarding OIP3 and estimated P1dB.

Currently, I calculate estimated P1dB from DC power, with 50% drain effciency.

Then OIP3 (dBm) was calculated from IM3 (dBc) based on the SCL output power. After that, I take a look at OIP3-estimated P1dB. I understand that the larger the difference shown the better performance.

But at this moment I am not sure, why is it so? what are the theoretical/practical reasons behind?

Thank you in advance for clearing my doubts.

Regards,

Jean

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Unread postPosted: Thu May 05, 2005 2:52 am

Hi Jean,

A well-known rull of thumb: OIP3 is 10dB higher than P1dB.

As you know, The OIP3 is a theoretical point that is obtained by linear extrapolation of the tangents for both the fundamental and third order curves, until they meet at a certain output power point - OIP3. The higher the difference between these 2 points the linear is the amplifier. That means you will obtain lower IM3 products for a given output power.

Usually, the OIP3 is measured at the linear region of the device.

If you have a bigger difference between P1dB and OIP3 that means for a higher power (higher than which OIP3 is measured) you will obtain lower IM3 products compared to an amplifier with that has a lower difference between these parameters.

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Jeanalmira

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Unread postPosted: Thu May 05, 2005 8:36 pm

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Joined: Tue Mar 15, 2005 11:43 pm

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Hi!

Thank you so much for the advice.

Truly appreciated :D

Regards,

Jean :wink:

Posted  11/12/2012