Similar to Design Notes, the steps for designing the external circuitry
of the two op amp INA is not different from the discrete method. The following list
describes the steps in the document covering the discrete design:
- Calculate the transfer function of
the circuit.
Equation 1.
- Select R4 and
R3 to set the minimum gain.
Equation 2.
- Select R1 and
R2. Make sure that R1 / R2 and
R3 / R4 ratios are matched to set the gain applied to
the reference voltage at 1V/V.
Equation 3.
- Select Rg to meet the
desired maximum gain G = 10V/V.
Equation 4.