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Improved OIP3

NickS

Apr 6, 2010
367
Joined
Apr 6, 2010
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367
Hello all,

I am working on an obsolescence re-design that required a high linearity amplifier operating from 1MHz to 30MHz. I am having some difficulty finding (50ohm) amplifiers in that frequency range that meet my needs since high frequencies are dominating the market now.

I feel like I am right on the boundary of having a solution. the SXB-2089Z covers nearly all my band which for now I will say is fine. but the P1dB is about 2dB low and the OIP3 is 1 dB low. In addition I have an OIP2 spec that is very very high. So the solution for 2 of the three problems if to combine two of the amps in a balanced design which buys me an extra 3dB on my P1dB and has the handy feature of canceling my OIP2 which makes that spec obtainable. But the final problem is OIP3. Does anyone know how to cheat an extra dB out of that?

I have a couple ideas but nothing that I feel completely confident in...
1) Run it at a higher bias voltage than nominal. This can often improve linearity though the price for it is more power dissipated and my current budget is already close to max.

2) I have read that a good output match is critical to reach the best possible IOP3.

Does anyone here have another suggestion or experience improving OIP3 with the ones above?

Thanks in advance
-Nick-
 
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