Figure 8-1 shows the use of OPAx863A in a second-order multifeedback (MFB) low-pass filter with a cut-off frequency of 2 MHz. The frequency response of the circuit in Figure 8-1 is compared for various amplifiers with different gain-bandwidth products and shown in Figure 8-2:

Figure 8-1 MFB Low-Pass Filter Circuit Using the OPAx863A

Table 8-1 provides the following benefits of using OPAx863A in an MFB low-pass filter circuit:

• High-precision measurements with low offset voltage across the operating temperature range for low-frequency signals in pass band
• High linearity due to the larger GBW and loop gain for low-frequency signals in pass band
• Higher accuracy of cutoff frequency and smaller variations over process and temperature
• Small integrated output noise due to low-pass filtering

Based on Figure 8-2, and as with the OPAx863A, use an amplifier with a gain bandwidth product at least 20 × greater than the filter cutoff frequency. This configuration results in a high-precision and high-linearity, low-pass-filter design.