Innovations in ultra-low-noise voltage references

High-resolution ADCs are more sensitive to voltage reference noise, which directly impacts voltage measurements because of their direct connection to data-conversion circuitry. Ultra-low-noise voltage references help high-resolution ADCs reach their full resolution potential. The REF70 has ultra-low 1/f noise that attaches with products that require ultra-low noise such as high-resolution ADCs or a multichannel analog front end such as the AFE2256. Adding low-pass filters on the output of the voltage reference lowers broadband noise and thus lowers system noise, as shown in Figure 8.

When designing a low-pass filter, it is important to ensure that the output impedance does not degrade AC performance. This can occur in resistor-capacitor low-pass filters where a large series resistance affects the load transients caused by output current fluctuations. Choose a low-pass filter bandwidth cutoff frequency under 10 Hz to limit the impact of broadband noise.