The full-power bandwidth curve has been a staple in data sheets for decades. The full-power bandwidth of an op amp provides some indication about where designers can expect slew-induced distortion on a signal of a given amplitude and frequency. The full-power bandwidth curve is generated using Equation 2.

Figure 6-3 shows the full-power bandwidth of the OPAx591. The curve is a good reference for designers that need to achieve high-voltage, high-frequency output swings with little concern for distortion performance. Unfortunately, the curve provides little indication of the true distortion at any given point on the curve. The full-power bandwidth curve is, after all, only a theoretical value and slew-induced distortion appears gradually as the output nears the maximum rate of change. Furthermore, slew-induced distortion is only one of several sources of op-amp distortion. Therefore, the curve is a decent starting point, but not a reliable source for distortion performance.

Figure 6-4 shows the full power bandwidth in terms of total harmonic distortion (THD) performance for the OPAx591. This curve provides a better indication of the level of distortion that a designer can expect for a signal of a given amplitude and frequency. For example, the OPAx591 can achieve approximately −100dB or better of THD at 70V_PP up to approximately 1kHz. As a second example, the OPAx591 can achieve approximately −130dB or better of THD at 10V_PP up to about 1kHz. As a result of limitations in measurement bandwidth, only 20kHz data are recorded.

Figure 6-3 Full-Power Bandwidth

Figure 6-4 Full-Power Bandwidth Improved