The OPAx197-Q1 feature high output-current-drive capability and low input offset voltage, making these devices an excellent reference buffer to provide an accurate buffered output with ample drive current for transients. For the 10-µF ceramic capacitor shown in Figure 8-4, a 37.4-Ω isolation resistor (R_ISO), provides separation of two feedback paths for optimal stability. Feedback path number one is through R_F and is directly at the output (V_OUT). Feedback path number two is through R_Fx and C_F and is connected at the output of the op amp. The optimized stability components shown for the 10-µF load give a closed-loop signal bandwidth at V_OUT of 4 kHz and still provide a loop gain phase margin of 89°. Any other load capacitances require recalculation of the stability components: R_F, R_Fx , C_F , and R_ISO.

Figure 8-4 Precision Reference Buffer