Many projects, such as those which make use of operational amplifiers, are highly dependent on their performance of feedback networks that makes use of passive components, i.e., resistors.
Thus, the gain of an operational and its stability are dependent on a resistive network, as shown in Figure 1.
However, we know that the resistors have a tolerance, which makes the actual value of this component vary and with that, if we have several operating amplifiers in a circuit, or an amplifier where the gain must be within a very wide range it may pose as a problem for the designer.
A simple way to obtain precision resistors, already coupled and placed in a single enclosure is with their integration.
Using BiCMOS technology, it is possible to integrate resistors accurately, so that in a project we do not have to worry about these components.
Maxim then offers the solution that consists of an "integrated circuit of resistors only" to be used in this type of application, as shown in Figure 2.
In Figure 3 we have the application of this integrated circuit formed by two resistors in a voltage divider configuration in a buffered input attenuator.
Integrated circuits of this type, made up only of resistors are MAX490, MAX5491 and MAX5492 with resistors of 100k, 30k and 10k.
See Maxim's complex application note at: https://www.maximintegrated.com/en/app-notes/index.mvp/id/4301
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