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
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Jim Thompson wrote:

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

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

On Sat, 30 Jun 2007 19:48:42 +0100, Chris Jones
wrote:

Jim Thompson wrote:

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

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

Customer has no clue... cut and pasted from someone else's data sheet
:-(

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

"Jim Thompson" schreef in
bericht ...
On Sat, 30 Jun 2007 19:48:42 +0100, Chris Jones
wrote:

Jim Thompson wrote:

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

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

Customer has no clue... cut and pasted from someone else's data sheet
:-(

...Jim Thompson

Guess you're on the wrong group. Seems a question for lawyers, not for
designers.

petrus bitbyter

Jim Thompson wrote:

On Sat, 30 Jun 2007 19:48:42 +0100, Chris Jones
wrote:

Jim Thompson wrote:

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

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

Customer has no clue... cut and pasted from someone else's data sheet
:-(

...Jim Thompson

I guess a safe bet would be to get hold of the competitor's part, measure it
under the conditions that the customer will be using, and make sure yours
will be better. You could also see if the competitor puts a measurement
setup in their data sheet. It gets more difficult if the customer is just
selling the chips and doesn't know how they are going to be used, or what
is important about their behaviour.

Chris

Jim Thompson wrote:

On Sat, 30 Jun 2007 19:48:42 +0100, Chris Jones
wrote:

Jim Thompson wrote:

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

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

Customer has no clue... cut and pasted from someone else's data sheet
:-(


Ask them WHICH data sheet.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

Jim Thompson wrote:

On Sat, 30 Jun 2007 19:48:42 +0100, Chris Jones
wrote:

Jim Thompson wrote:

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

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

Customer has no clue... cut and pasted from someone else's data sheet
:-(

...Jim Thompson
I think your first decision is to guess whether they care about differential
or integral non-linearity.
--
JosephKK
Gegen dummheit kampfen die Gotter Selbst, vergebens.Â*Â*
--Schiller

Jim Thompson wrote:

On Sat, 30 Jun 2007 19:48:42 +0100, Chris Jones
wrote:

Jim Thompson wrote:

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

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

Customer has no clue... cut and pasted from someone else's data sheet
:-(

Sounds like you are working for my old employer. They had a curve
specified in a document that had survived from WWII (the B29 I think).
Someone discovered that it was drawn, or copied backwards and had been
for years. Nobody cared, as the vendors just built systems that worked
rather than to our specs.

As a joke, someone added a reference in a preliminary copy of our
document to Mil spec MIL-TFD-41C, "Make it like the f*ing drawing, for
once".

--
Paul Hovnanian
------------------------------------------------------------------
This is the government our founding fathers warned us about.

On Mon, 09 Jul 2007 18:07:23 -0700, "Paul Hovnanian P.E."
wrote:

Jim Thompson wrote:

On Sat, 30 Jun 2007 19:48:42 +0100, Chris Jones
wrote:

Jim Thompson wrote:

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

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

Customer has no clue... cut and pasted from someone else's data sheet
:-(

Sounds like you are working for my old employer. They had a curve
specified in a document that had survived from WWII (the B29 I think).
Someone discovered that it was drawn, or copied backwards and had been
for years. Nobody cared, as the vendors just built systems that worked
rather than to our specs.

As a joke, someone added a reference in a preliminary copy of our
document to Mil spec MIL-TFD-41C, "Make it like the f*ing drawing, for
once".

Sno-o-o-o-ort!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

i loved the term "as built" specs !

we were the "muthus of invenchuns", but the stuf was built from experience,
instead of textbook theory! and it worked too!

so there! you smarmy school teached bums!

:=))


"Jim Thompson" wrote in
message ...
On Mon, 09 Jul 2007 18:07:23 -0700, "Paul Hovnanian P.E."
wrote:

Jim Thompson wrote:

On Sat, 30 Jun 2007 19:48:42 +0100, Chris Jones
wrote:

Jim Thompson wrote:

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

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

Customer has no clue... cut and pasted from someone else's data sheet
:-(

Sounds like you are working for my old employer. They had a curve
specified in a document that had survived from WWII (the B29 I think).
Someone discovered that it was drawn, or copied backwards and had been
for years. Nobody cared, as the vendors just built systems that worked
rather than to our specs.

As a joke, someone added a reference in a preliminary copy of our
document to Mil spec MIL-TFD-41C, "Make it like the f*ing drawing, for
once".

Sno-o-o-o-ort!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Chris Jones wrote:

Jim Thompson wrote:

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

Better ask the customer. (Even if they are not correct in their
definition, it is their definition that you need to know.)
Chris
Aye, but the customer may not "know" either, it may just be a sales spec.
Do you have a quantifiable specification definition? I have one but it may
not match the the customers "idea" of the requirement. Check a/d and d/a
specifications, they are very similar to my method.
--
JosephKK
Gegen dummheit kampfen die Gotter Selbst, vergebens.Â*Â*
--Schiller

On Sat, 30 Jun 2007 10:30:53 -0700, Jim Thompson
wrote:

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

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

On Sat, 30 Jun 2007 12:15:19 -0700, John Larkin
wrote:

On Sat, 30 Jun 2007 10:30:53 -0700, Jim Thompson
wrote:

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

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


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

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

On Sat, 30 Jun 2007 12:15:19 -0700, the renowned John Larkin
wrote:

On Sat, 30 Jun 2007 10:30:53 -0700, Jim Thompson
wrote:

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

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

Except for marketing types.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

On Sat, 30 Jun 2007 18:47:59 -0500, Spehro Pefhany
wrote:

On Sat, 30 Jun 2007 12:15:19 -0700, the renowned John Larkin
wrote:

On Sat, 30 Jun 2007 10:30:53 -0700, Jim Thompson
wrote:

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

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

Except for marketing types.


Do marketing types know how to divide?

John

John Larkin wrote:


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

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

Except for marketing types.



Do marketing types know how to divide?


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

http://www.abvolt.com

Vladimir Vassilevsky a écrit :


John Larkin wrote:


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

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

Except for marketing types.


Do marketing types know how to divide?


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


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


--
Thanks,
Fred.

On Sat, 30 Jun 2007 10:30:53 -0700, Jim Thompson
wrote:

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

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

See:

http://www.maxim-ic.com/appnotes.cfm...te_number/740/

http://www.maxim-ic.com/appnotes.cfm...te_number/748/

Maybe your customer is thinking of something along these lines.

On Sat, 30 Jun 2007 13:20:34 -0700, The Phantom wrote:

On Sat, 30 Jun 2007 10:30:53 -0700, Jim Thompson
wrote:

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

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

See:

http://www.maxim-ic.com/appnotes.cfm...te_number/740/

http://www.maxim-ic.com/appnotes.cfm...te_number/748/

Maybe your customer is thinking of something along these lines.


Regardless, nice links... thanks.

On Sat, 30 Jun 2007 13:20:34 -0700, The Phantom
wrote:

On Sat, 30 Jun 2007 10:30:53 -0700, Jim Thompson
wrote:

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

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

See:

http://www.maxim-ic.com/appnotes.cfm...te_number/740/

http://www.maxim-ic.com/appnotes.cfm...te_number/748/

Maybe your customer is thinking of something along these lines.

Thanks!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

On Sat, 30 Jun 2007 10:30:53 -0700, Jim Thompson wrote:

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

When I teach classes and seminars one of my hobby horses is the
definitions of words. Some things have a pretty well defined meaning, but
there are a whole bunch of words and phrases (% linearity, for instance),
that have no consistent across-the-board meaning. I try to target 80 or
90% comprehension, which means that I get about 50% of the class rolling
their eyes at me.

Were it me, I'd ask my customer to define what _they_ mean by it; if I
think they know enough to be dangerous and no more, I may even preface my
questions by saying "y'know, different segments of the market define this
differently...".

I suspect they mean "linearity" in the same sense that "integral linearity"
is defined in an op-amp -- but even there I bet the definition varies with
the vendor.

Further, if you deliver an amplifier to them that's perfectly linear
except for a crossover distortion that's 0.25% of full scale output
they'll be unhappy with your "0.25% linearity".

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

On Sat, 30 Jun 2007 18:22:10 -0500, Tim Wescott
wrote:

Further, if you deliver an amplifier to them that's perfectly linear
except for a crossover distortion that's 0.25% of full scale output
they'll be unhappy with your "0.25% linearity".


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

"Jim Thompson" wrote in
message ...
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?

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

Colin =^.^=

colin wrote:
"Jim Thompson" wrote in
message ...
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?

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

Colin =^.^=



Ya mean something like 99.75% distortion? ;-)

Jim Thompson wrote:
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
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

On Sun, 01 Jul 2007 11:55:39 GMT, Stanislaw Flatto
wrote:

Jim Thompson wrote:
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
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

Sno-o-o-ort ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Stanislaw Flatto wrote:

Jim Thompson wrote:
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
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


You _can_ draw a straight line through any three points if you're a
great comic!!!



--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

Jim Thompson wrote:
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

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.

"Jim Thompson" wrote in
message ...
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
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

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

Jure Z.

On Sun, 01 Jul 2007 13:58:27 GMT, "Jure Newsgroups"
wrote:


"Jim Thompson" wrote in
message ...
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


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

Jure Z.


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
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

"Jim Thompson" wrote in
message ...
On Sun, 01 Jul 2007 13:58:27 GMT, "Jure Newsgroups"
wrote:


"Jim Thompson" wrote in
message ...
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


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

Jure Z.


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
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave


the consequence may then be : a minimum Avol is required to achieve that
maximum percent linearity error relative to full dynamic range.
( and here I assumed a few implicit meanings..., disregarding the dynamics,
and only looking at the steady state or DC "final value".)

Jure Z.

On Sun, 01 Jul 2007 09:01:00 -0700, Jim Thompson
wrote:

On Sun, 01 Jul 2007 13:58:27 GMT, "Jure Newsgroups"
wrote:


"Jim Thompson" wrote in
message ...
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


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

Jure Z.


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


So just overkill a 0.25% best-straight-line fit by 10:1 or so, and
they can't complain.

John

John Larkin a écrit :
On Sun, 01 Jul 2007 09:01:00 -0700, Jim Thompson
wrote:

On Sun, 01 Jul 2007 13:58:27 GMT, "Jure Newsgroups"
wrote:

"Jim Thompson" wrote in
message ...
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
Jim, is that the spec for a ramp generator, or a scanning amplifier ?

Jure Z.

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


So just overkill a 0.25% best-straight-line fit by 10:1 or so, and
they can't complain.

Sure thay can:

....
" That's overkill! Couldn't you have done it cheaper?"


--
Thanks,
Fred.

On Sun, 01 Jul 2007 21:07:55 +0200, the renowned Fred Bartoli
r_AndThisToo wrote:

John Larkin a écrit :
On Sun, 01 Jul 2007 09:01:00 -0700, Jim Thompson
wrote:

On Sun, 01 Jul 2007 13:58:27 GMT, "Jure Newsgroups"
wrote:

"Jim Thompson" wrote in
message ...
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
Jim, is that the spec for a ramp generator, or a scanning amplifier ?

Jure Z.

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


So just overkill a 0.25% best-straight-line fit by 10:1 or so, and
they can't complain.

Sure thay can:

...
" That's overkill! Couldn't you have done it cheaper?"

"Not and be sure of maintaining production yields".


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Jim Thompson wrote:

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

You've got big problems with that DC gain of 300 assuming reasonable
full scale output range specified, seeing as how most of your stuff is
LV MOS. The parrots seem to be hung up on "best" straight line fit etc
when in fact the specification is maximum deviation of actual from ideal
as a percent full scale range...

On Mon, 02 Jul 2007 04:59:34 GMT, Fred Bloggs
wrote:



Jim Thompson wrote:

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

You've got big problems with that DC gain of 300 assuming reasonable
full scale output range specified, seeing as how most of your stuff is
LV MOS. The parrots seem to be hung up on "best" straight line fit etc
when in fact the specification is maximum deviation of actual from ideal
as a percent full scale range...

"Linearity" is ususally not the same as absolute accuracy, but that's
a matter of application and definition.

John

On Mon, 02 Jul 2007 04:59:34 GMT, Fred Bloggs
wrote:



Jim Thompson wrote:

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

You've got big problems with that DC gain of 300 assuming reasonable
full scale output range specified, seeing as how most of your stuff is
LV MOS. The parrots seem to be hung up on "best" straight line fit etc
when in fact the specification is maximum deviation of actual from ideal
as a percent full scale range...

Naaah! You're talking to the master here. I'm getting 0.03%
deviation from a best-fit straight line. Plus I'm nulling (auto-zero)
the amplifier before each measurement.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

On Mon, 02 Jul 2007 07:28:02 -0700, Jim Thompson
wrote:

On Mon, 02 Jul 2007 04:59:34 GMT, Fred Bloggs
wrote:



Jim Thompson wrote:

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

You've got big problems with that DC gain of 300 assuming reasonable
full scale output range specified, seeing as how most of your stuff is
LV MOS. The parrots seem to be hung up on "best" straight line fit etc
when in fact the specification is maximum deviation of actual from ideal
as a percent full scale range...

Naaah! You're talking to the master here. I'm getting 0.03%
deviation from a best-fit straight line. Plus I'm nulling (auto-zero)
the amplifier before each measurement.

...Jim Thompson

Yup, gain is cheap these days. Linearity is dominated by the feedback
resistors.

John

In article ,
Jim Thompson wrote:

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

Depends if you are the customer or supplier. If you
are the supplier then you want the widest barn door.

Assume Gain = K = dVout/dVin, measured over the
widest possible swing of Vout, dVoutmax/dVinmax.

"0.25% linearity" is the departure from the straight
line as a percentage of Voutmax... = Voutmax/400.

"DC-offset" is the value of Vout when Vin=0 for the
particular device under test.

Vout = K*Vin +/- (Voutmax/400) +/- (DC-offset).

So to verify any particular DUT.

Measure and record DC-offset and K for that device.

Then measure Vout for a range of Vin = 0 to Voutmax/K.

If the DUT is in spec, then for all plotted values of Vin:-


(Vout - K*Vin -/+ DC-offset) = +/- Voutmax/400

--
Tony Williams.

On Mon, 02 Jul 2007 09:56:01 +0100, Tony Williams
wrote:

In article ,
Jim Thompson wrote:

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

Depends if you are the customer or supplier. If you
are the supplier then you want the widest barn door.

Assume Gain = K = dVout/dVin, measured over the
widest possible swing of Vout, dVoutmax/dVinmax.

"0.25% linearity" is the departure from the straight
line as a percentage of Voutmax... = Voutmax/400.

"DC-offset" is the value of Vout when Vin=0 for the
particular device under test.

Vout = K*Vin +/- (Voutmax/400) +/- (DC-offset).

So to verify any particular DUT.

Measure and record DC-offset and K for that device.

Then measure Vout for a range of Vin = 0 to Voutmax/K.

If the DUT is in spec, then for all plotted values of Vin:-


(Vout - K*Vin -/+ DC-offset) = +/- Voutmax/400

What I'm doing, though I'm sure it over states the error is...

(V(OUTP,OUTN)-(MAX(V(OUTP,OUTN))-MIN(V(OUTP,OUTN)))/6m*V_VSW)

in PSpice Probe, since I have 65 process corners to test :-(

(6mV is the input sweep, V_VSW is the name of the source)

The gives the classic error "S-curve" _except_ the end point are at
zero instead of the usual even spread about zero error.

Since I have 65 sets to do I'm trying to avoid best-fit for each :-(

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave