Definition of Linearity

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Jim Thompson 19 years ago

I have a specification for an amplifier design that says "0.25% linearity".

I can't seem to lay my hands on a precise definition of what that means.

Likewise... How to calculate?

...Jim Thompson

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| 1962 | America: Land of the Free, Because of the Brave

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Chris Jones 19 years ago

Better ask the customer. (Even if they are not correct in their definition, it is their definition that you need to know.) Chris

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John Larkin 19 years ago

Probably peak deviation from best straight-line fit, as a percentage of full-scale swing. Most people would use half of rail-rail output swing (ie, peak, not p-p) as the denominator.

John

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The Phantom 19 years ago

The data converter people have some measures of non-linearity.

See:

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Maybe your customer is thinking of something along these lines.

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Jim Thompson 19 years ago

That's sort of what I was musing. Now to implement it in PSpice.

...Jim Thompson

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Spurious Response 19 years ago

Regardless, nice links... thanks.

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Jim Thompson 19 years ago

Thanks!

...Jim Thompson

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John Larkin 19 years ago

Do marketing types know how to divide?

John

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Vladimir Vassilevsky 19 years ago

The max. deviation from the straight line is a very complex concept. Probably they ment the THD of 0.25%

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

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Spehro Pefhany 19 years ago

Except for marketing types.

Best regards, Spehro Pefhany

"it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com

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Spurious Response 19 years ago

Shouldn't one question be 'what type of amp is this?' Like audio amp, rf amp, etc.?

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colin 19 years ago

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

wouldnt that just translate to 0.25% voltage distortion ? I assume that 0.25% is a linearity , otherwise it would be a rather poor amplifier.

Colin =^.^=

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PhattyMo 19 years ago

Ya mean something like 99.75% distortion? ;-)

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Stanislaw Flatto 19 years ago

It relates to well known definition that says "You _can_ draw a straight line through any three points if it is thick enough".

HTH

Stanislaw

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Fred Bloggs 19 years ago

The very word almost invariably refers to A/D errors these days, and typically specifies 1/2LSB maximum error due to all amplifier characteristics: offsets, gain errors, rolloff. The 0.25% would be approximately 1/2LSB for an 8-bit.

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Fred Bartoli 19 years ago

Vladimir Vassilevsky a écrit :

...which then is the rms deviation from straight line. Not a much simpler concept I'm afraid :-)

Thanks, Fred.

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Jure Newsgroups 19 years ago

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Jim, is that the spec for a ramp generator, or a scanning amplifier ?

Jure Z.

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Phil Allison 19 years ago

"Fred Bartoli"

** The world recognised, published authorities on this topic are messrs:

Dave Dee, Dozy, Beaky, Mick and Titch.

Their seminal 1966s work on "linearity " was mischievously entitled " Bend It ".

Not another word needs to be said .......

........ Phil

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Jim Thompson 19 years ago

Sno-o-o-ort ;-)

...Jim Thompson

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Jim Thompson 19 years ago

It's an amplifier with less than 10KHz bandwidth (to get quick settling), gain of 300, but it's essentially a DC signal.

...Jim Thompson

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Definition of Linearity

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