The voltage reference for this application should have the following features:

1. Dual output (3.0 V and 1.5 V),
2. Low drift, and
3. Low tracking errors between the two outputs.

For this design, the REF2030 is used. The REF20xx topology is as shown in the Section 9.2 section.

The REF2030 is an excellent choice for this application because of its dual output. The temperature drift of
8 ppm/°C and initial accuracy of 0.05% make the errors resulting from the voltage reference minimal in this application. In addition, there is minimal mismatch between the two outputs and both outputs track very well across temperature, as shown in Figure 10-4 and Figure 10-5.

Figure 10-4 V_REF – 2 × V_BIAS Distribution (At T_A = 25°C)

Figure 10-5 Distribution of V_REF – 2 × V_BIAS Drift Tracking Over Temperature