Amplifier with higher OIP3/IIP3 the more linear it is?
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From: G Patel on 12 Jun 2010 19:07 Does higher OIP3/IIP3 mean more linearity?
From: Tim Wescott on 12 Jun 2010 21:00 On 06/12/2010 04:07 PM, G Patel wrote: > Does higher OIP3/IIP3 mean more linearity? Probably. In general. Maybe. Equate IP3 with linearity, and see manufacturers start making crappy amplifiers with great IP3 specs. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
From: j on 14 Jun 2010 13:52 On Jun 12, 6:00 pm, Tim Wescott <t...(a)seemywebsite.now> wrote: > On 06/12/2010 04:07 PM, G Patel wrote: > > > Does higher OIP3/IIP3 mean more linearity? > > Probably. In general. Maybe. > > Equate IP3 with linearity, and see manufacturers start making crappy > amplifiers with great IP3 specs. > > -- > Tim Wescott > Control system and signal processing consultingwww.wescottdesign.com not sure what tim is trying to say ... but yes OIP3 is the accepted linearity spec for RF amps. drawing conclusions about spectral regrowth with digital signals can be a challenge sometimes, but for sine signals it is a direct correlation to linearity. i've experienced vendors who use OIP3 in non 50 ohm systems as an attempt to make their spec's look better. a/d drive amps are a particular example. jdc
From: Tim Wescott on 14 Jun 2010 16:56
On 06/14/2010 10:52 AM, j wrote: > On Jun 12, 6:00 pm, Tim Wescott<t...(a)seemywebsite.now> wrote: >> On 06/12/2010 04:07 PM, G Patel wrote: >> >>> Does higher OIP3/IIP3 mean more linearity? >> >> Probably. In general. Maybe. >> >> Equate IP3 with linearity, and see manufacturers start making crappy >> amplifiers with great IP3 specs. >> >> -- >> Tim Wescott >> Control system and signal processing consultingwww.wescottdesign.com > > > not sure what tim is trying to say ... but yes OIP3 is the accepted > linearity spec for RF amps. drawing conclusions about spectral > regrowth with digital signals can be a challenge sometimes, but for > sine signals it is a direct correlation to linearity. I meant "Apply that specification outside of radio (where it makes sense)" etc., etc. > i've experienced vendors who use OIP3 in non 50 ohm systems as an > attempt to make their spec's look better. a/d drive amps are a > particular example. For a while Motorola was specifying their CATV amps in some unusual way -- either 3IM with multiple input tones, or 5IM, I can't remember which. And I don't know if they still do, or if anyone cares in this digital age. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com |