Help: How to understand this sentence?

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

-- Deep Fryer: a very philosophical monk. Website:

"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

Thank you very much for answering my questions. And now I can understand what's that mean.

You're very welcome.

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

Mark L. Fergerson

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.