_Cheap_ Instrumentation Amplifier?

As I recall, National recently came out with an Op Amp that had the resistors included on the chip, for several gain options including zero.

Don

Linear Technology makes an opamp with onboard resistors; the LT1991 [

My first option is the AD620 if performance matters, or the cheaper and lesser speced AD623 for general purpose jobs. No resistor required for unity gain. They may not be "low spec" enough for you though, so might blow your budget. About $3.50ea in one-off qty at digikey for the AD623

Dave :)

I like the way Analog doesn't lock the datasheets. For example, I was able to add your price as a comment. And they have a mistake in the gain formula in the figure on page 13, so I simply used the "Touch-Up Text" tool and fixed and saved it! Very satisfying.

I don't think I've seen one for less than a dollar. In the $1-$2 range in 1K, there are plenty of them, depending on what you want to do about gain setting etc. Try a parametric search at AD & National. This brand new one at a very reasonable $1.30/1K looks pretty cool:

Insanely gross overkill for your application, but so what? Maybe you can cut corners on some of those external parts.

Best regards, Spehro Pefhany

Your modest requirements, and R-paks -- cheap, small, and often ratiometrically pretty good -- might make for a marraige of convenience, if not ultimate beauty?

Regards, James Arthur

.................................................................... marriage, gosh darn it.

James "Typos shall not be revealed until akready[sic] posted." -- Cosmic USENET Policy

not exactly a inst amp, but INA2134 from TI might be worth investigating, 8 pin dip, Zin is a bit low, o/p offset a bit high, cmrr good

but 4R's and an opamp is still the cheapest

martin

On 15/12/2005 the venerable Anonymous Coward etched in runes:

The Analog Devices AMP04 is one I have used in large numbers. It needs a single resistor for gain control.