8.2.3 Driving ADCs

The OPAx320-Q1 series op amps are an excellent choice for driving sampling analog-to-digital converters (ADCs) with sampling speeds up to 1 MSPS. The zero-crossover distortion input stage topology allows the OPAx320-Q1 to drive ADCs without degradation of differential linearity and THD.

The OPAx320-Q1 can be used to buffer the ADC switched input capacitance and resulting charge injection while providing signal gain. Figure 42 shows the OPAx320-Q1 configured to drive the ADS8326.

Figure 41. Two Op-Amp Instrumentation Amplifier With Improved High-Frequency Common-Mode Rejection

1.

NOINDENT:

Suggested value; may require adjustment based on specific application.

2.

NOINDENT:

Single-supply applications lose a small number of ADC codes near ground as a result of op amp output swing limitation. If a negative power supply is available, this simple circuit creates a –0.3-V supply to allow output swing to true ground potential.

Figure 42. Driving the ADS8326