The OPA698 is a voltage-feedback amplifier that combines features of a wideband, high-slew-rate amplifier with output-voltage limiters. The output swings up to 1V from each rail and delivers up to 190mA. These capabilities makes this device an excellent choice to drive ADCs while adding overdrive protection for the ADC inputs.

Figure 8-8 shows the dc-coupled, gain of 2V/V, dual power-supply circuit configuration used as the basis of the ±5V electrical characteristics and typical characteristics. For test purposes, the input impedance is set to 50Ω with a resistor to ground and the output impedance is set to 500Ω. Voltage swings reported in the specifications are taken directly at the input and output pins. For the circuit of Figure 8-8, the total output load is 500Ω || 804Ω = 308Ω. The voltage limiting pins are set to ±2V through a voltage divider network between the +V_S and ground for V_H, and between – V_S and ground for V_L. These limiter voltages are adequately bypassed with a 0.1µF ceramic capacitor to ground. The limiter voltages (V_H and V_L) and the respective bias currents (I_VH and I_VL) have the polarities shown. One additional component is included in Figure 8-8. An additional resistor (174Ω) is included in series with the noninverting input. Combined with the 25Ω dc source resistance directed back towards the signal generator, an input bias current-canceling resistance is obtained that matches the 200Ω source resistance seen at the inverting input; see also Section 8.1.9. The power-supply bypass for each supply in Figure 8-8 consists of two capacitors: one electrolytic 2.2µF and one ceramic 0.1µF. Figure 8-8 and Figure 8-9 explicitly show the power-supply bypass capacitors, but is assumed in the other figures. An additional 0.01µF power-supply decoupling capacitor (not shown here) can be included between the two power-supply pins.