Noise (ppmp-p)

0.00

0.03

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0

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Figure 8-5. 0.1Hz to 10Hz Voltage Noise Distribution

The 1/f noise is in such a low frequency range that it is not practical to filter out which makes it a key parameter

for ultra-low noise measurements. Noise sensitive designs must use the lowest 1/f noise for the highest precision

measurements. Figure 8-6 shows the effect of 1/f noise over 10s.

Time (1s/div)

Figure 8-6. 0.1Hz to 10Hz Voltage Noise

8.3.2 Broadband Noise

Broadband noise is a noise that appears at higher frequency compared to 1/f noise. The broadband noise is

dominated by white noise as shown in Figure 8-8 . The broadband noise is measured by high-pass filtering

the output of the REF80 and measuring the result on a spectrum analyzer as shown in Figure 8-7. The DC

component of the REF80 is removed by using a high-pass filter and then amplified. When measuring broadband

noise, it is not necessary to have high gain to achieve maximum bandwidth.

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REF80

SNAS856 – SEPTEMBER 2024

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