8.2.2 Detailed Design Procedure

Use Equation 1 and Equation 2 to calculate the required gain for the inverting amplifier:

Equation 1.

Equation 2.

When the desired gain is determined, select a value for R_I or R_F. Selecting a value in the kilohm range is desirable for general-purpose applications because the amplifier circuit uses currents in the milliamp range. This milliamp current range ensures the device does not draw too much current. The trade-off is that large resistors (hundreds of kilohms) draw the smallest current but generate the highest noise. Small resistors (hundreds of ohms) generate low noise but draw high current. In this example, R_I equals 10 kΩ, and R_F equals 36 V. Equation 3 determines these values:

Equation 3.