8.2.3 Precision Reference Buffer

The OPAx197 features high output current drive capability and low input offset voltage, making the device 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 56, R_ISO, a 37.4-Ω isolation resistor, 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, while still providing 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 56. Precision Reference Buffer