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Help: How to understand this sentence?

L

Loamlo

Jan 1, 1970
0
I am reading an article on OP Amp. And there is such a paragraph as
following:

"Details of op amp input and output structures are also covered in this
chapter, with emphasis on how such factors potentially impact
application performance.In some senses, it is logical to categorize op
amp types into performance and/or application classes, a process that
works to some degree, but not altogether."

What's the "performance and/or application classes" mean? Two classes?
Then what's the "performance class"?

Thank you very much in advance.
 
T

Tim Williams

Jan 1, 1970
0
Loamlo said:
What's the "performance and/or application classes" mean? Two classes?
Then what's the "performance class"?

Keep reading and you'll find out. Performance refers to desirable
characteristics: noise, input and output currents and voltages, frequency
capacity, slew rate, etc.

Tim
 
M

Mark Fergerson

Jan 1, 1970
0
Loamlo said:
I am reading an article on OP Amp. And there is such a paragraph as
following:

"Details of op amp input and output structures are also covered in this
chapter, with emphasis on how such factors potentially impact
application performance.In some senses, it is logical to categorize op
amp types into performance and/or application classes, a process that
works to some degree, but not altogether."

What's the "performance and/or application classes" mean? Two classes?
Then what's the "performance class"?

"Performance classes" usually means segregating parts by some
specific property/properties of the parts; speed, bandwidth, temp range,
and like that.

"Application classes" usually means other engineers have tried
various parts in various apps and found that certain parts are better
than others in specific apps because of the particular combination of
properties a given part has. It may also mean that a class of parts was
specifically designed to optimize properties desired for say lock-in
amps or whatever.

"Not altogether" comes in because often you can't just plug somebody
else's recommendation for say an instrument amp into your design because
you may have a different temp range spec or whatever; you may have to
wade back into the "performance" specs and end up selecting a part
designed for a different purpose.

Keyword for the day; "tradeoffs".


Mark L. Fergerson
 
L

Loamlo

Jan 1, 1970
0
Thank you very much for answering my questions.
And now I can understand what's that mean.
 
M

Mark Fergerson

Jan 1, 1970
0
Loamlo said:
Thank you very much for answering my questions.

You're very welcome.
And now I can understand what's that mean.

Just part of getting from textbooks to reality. Expect more of the
same as you go along.


Mark L. Fergerson
 
D

Dr Engelbert Buxbaum

Jan 1, 1970
0
Loamlo wrote:

"Details of op amp input and output structures are also covered in this
chapter, with emphasis on how such factors potentially impact
application performance.In some senses, it is logical to categorize op
amp types into performance and/or application classes, a process that
works to some degree, but not altogether."

What's the "performance and/or application classes" mean? Two classes?
Then what's the "performance class"?

Do you need a particularly high input impedance from a FET input or does
bipolar suffice? Is a particularly low noise level required, or would
you prefer high output current or may be a high slew rate instead? Do
you want single-rail operation? Do you need the max. output voltage to
be close to the supply voltage or would a little lower do?

An introduction to OpAmps will cover the so called "ideal OpAmp" with
infinite input impedance, zero output impedance, infinite slew rate, no
bias, no noise and so on. Real OpAmps are technical compromises that
come close to some of those features, at the expense of others.
 
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