Looking for three smt precision resistors in a single chip

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cmartinez

Joined Jan 17, 2007
7,080
Anyone here knows if there are sets of high-quality, low temp coefficient, high-precision resistors out there that could be used to set the gain of OpAmps or instrumentation amplifiers in a single package?

I would've guessed that there should exist a commercial chip with the three high quality resistors inside it already set at a fixed gain ratio as shown in this schematic:

upload_2017-12-4_11-49-46.png

The gain in this opamp configuration (which is extremely common) is always defined as G = 1 + 2*Rf/Rg. I would've thought that there already were 4-pin chips in the market that could be used for this purpose.

Instead, I've had to browse through hundreds of different options at Digikey, Newark and Mouser to see if I can find a proper, affordable combination of those resistors, and it's been a real pain. This because prices vary wildly (from a few cents up to more than $70.00 dlls apiece) from one manufacturer to another, even if their specs are exactly the same.
 

GopherT

Joined Nov 23, 2012
8,012
I would get a 4-pin 2-resistor array for Rf and a low temp-co single Rg in series with a low-value trimmer for final adjustment of gain.
 
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