GAIN SELECTION
The gain of the AD623 is resistor programmed by RG, or more precisely, by whatever impedance appears between Pin 1 and Pin 8. The AD623 is designed to offer accurate gains using 0.1% to 1% tolerance resistors. Table 5 shows the required values of RG for the various gains. Note that for G = 1, the RG terminals are unconnected (RG = ∞). For any arbitrary gain, RG can be calculated by
RG = 100 kΩ/(G − 1)