The traditional SAR converter has the reference transients illustrated in Figure 1-2. Some modern SAR converters, like the ADS9218, provide an integrated voltage reference buffer. In this case the input impedance of the ADC reference input pin is high and no transients are present. Generally, the high-impedance buffer has a low input-leakage current in nanoamps. Traditional ADCs without integrated reference buffers require some kind of external buffer such as shown in Figure 1-1. Modern data converters with the integrated reference buffer do not require any external buffer and are much more flexible in terms of what reference can be used. The integrated buffer can also allow a simple RC filter between the reference and the ADC for noise reduction. Properly conditioning the voltage reference for traditional converters with the transient current demand can be a challenging problem and is covered in Driving the SAR Reference video series.