SNVSCN7A November 2023 – December 2023 REF54
PRODUCTION DATA
1/f noise, also known as flicker noise, is dominant mostly in the lower frequency bands. REF54 data sheet specifies flicker noise for 0.1 Hz to 10 Hz frequency band where 1/f noise has maximum power. Since the 1/f noise is an extremely low value, the frequency of interest is amplified and filtered through a precise band filter with very low noise floor as shown in Figure 7-3.
Figure 7-4 shows typical distribution of flicker noise for multiple devices where more than 1000 samples have been captured for each device.
Noise sensitive designs prefer the lowest 1/f noise for the highest precision measurements. REF54 offers NR pin which creates a low pass filters on the band gap with typical resistance of 13 kΩ. 100 μF capacitor on NR pin removes the whole band of flicker noise (0.1 Hz) from the band gap refernce as shown in Figure 7-5. 10 μF capacitor on NR pin creates 1 Hz low pass filter fo bandgap.