AN1034

When analog switches are used either to select an op amp input, or to change op amp gain, minor circuit rearrangements can frequently enhance accuracy. In Figure 1, R of the input selector switch adds to R , ON 1 reducing gain and allowing gain to change with temperature. By switching into  a non inverting amplifier (b), gain change becomes negligible. Similarly, in a gain switching circuit, R is part of the gain determining  network  in  ( c),    but has ON neglible effect in (d).