The THS3001 is fabricated using Texas Instruments 30V complementary bipolar process, HVBiCOM. This process provides the excellent isolation and extremely high slew rates that result in excellent distortion characteristics.

As with all current-feedback amplifiers, the bandwidth of the THS3001 is an inversely proportional function of the value of the feedback resistor (see Figures 26 to 34). Table 7-1 shows the recommended resistors for an optimized frequency response. Use these values as a starting point, and after optimized values are found, use a 1% tolerance resistors to maintain frequency response characteristics. For most applications, a feedback resistor value of 1kΩ is recommended, a good compromise between bandwidth and phase margin that yields a stable amplifier.

Consistent with current-feedback amplifiers, increasing the gain is best accomplished by changing the gain resistor, not the feedback resistor. The reason is because the bandwidth of the amplifier is dominated by the feedback resistor value and internal dominant-pole capacitor. The ability to control the amplifier gain independent of the bandwidth constitutes a major advantage of current-feedback amplifiers over conventional voltage-feedback amplifiers. Therefore, after a frequency response is found that is designed for a particular application, adjust the value of the gain resistor to increase or decrease the overall amplifier gain.

Finally, make sure to realize the effects of the feedback resistance on distortion. Increasing the resistance decreases the loop gain and increases the distortion. Knowing that decreasing load impedance increases total harmonic distortion (THD) is also important Typically, the third-order harmonic distortion increases more than the second-order harmonic distortion.