In figure 58 of its data sheet, the ADA4927 is shown in a configuration where it is driving a capacitive load, but I do not see any data sheet specifications regarding this amplifier's ability to drive a capacitive load. So, is this amplifier unconditionally stable for any capacitive load?
Hi AlexRassekh,
Good day.
Figure 58 shows how the ADA4927 drives an ADC in which the capacitive loading was part of a second-order, low-pass filter with a cut-off frequency of 100 MHz. In the "Theory of Application" section, the closed-loop bandwidth as well as the stability of the amplifier is actually dependent on the feedback resistors. It was also stated that the elements used in the feedback loops must be resistive with values that ensure stability and sufficient bandwidth.
I have tried simulating a similar circuit as that of Figure 58. Driving the output of the op-amp with similar components and shown below is the result with no ringing, overshoots, and oscillations observed.
Ideally, for any amplifier design, a stable op-amp with an output resistance of 0 will drive any capacitive load without phase degradation. However, in practice, the stability of the circuit is often affected by the capacitive load. The values of the resistances and capacitances in the figure were selected in particular to achieve the optimum performance of the circuit. Sharing with you some application notes and articles regarding the capacitive loading in op-amp.
Thank you.
Regards,
Gilbeys
