Ambient Te mperature [

C]

0

10

20

30

40

50

60

70

-10

-5

0

5

10

15

Avg

Avg- Std dev

Avg+Std dev

Figure 8-2. Output Voltage Vs Free-Air Temperature

Te mperature Drift (ppm/

C) TA = 0C to 70C

0

10

20

30

40

50

0.02

0.04

0.06

0.08

0.1

0.12

Figure 8-3. Temperature Drift Distribution

8.3 Noise Performance

8.3.1 1/f Noise

1/f noise, also known as flicker noise, is dominant mostly in the lower frequency bands. Flicker noise affects the

device output voltage which can affect the ENOB of the signal chain. REF80 data sheet specifies flicker noise for

0.1Hz to 10Hz frequency band where 1/f noise has maximum power. Flicker noise is measured by filtering the

output from 0.1Hz to 10Hz. Since the 1/f noise is an extremely low value, the frequency of interest needs to be

amplified and band-pass filtered as shown in Figure 8-4. 1/f noise must be tested in a Faraday cage enclosure

to block environmental noise. Refer to application note Techniques for Noise Measurements in Precision Series

References for more detail on noise measurement for precision series references.

CL

High-pass Filter

FC = 0.07 Hz

Low Noise

Preamplifier

G = 1000

2

nd Order

Low-pass Filter

FC = 10 Hz

G = 1

2

nd Order

Low-pass Filter

FC = 10 Hz

G = 10

2

nd Order

High-pass Filter

FC = 0.1 Hz

G = 10

Scope

VDD

REF_Z

REF_GND_F

REF_GND_S

HEATP

HEATM

+15 V

-15 V

10 V

REF80

Figure 8-4. 1/f Noise Test Setup

Typical 1/f noise (0.1Hz to 10Hz) distribution can be seen in Figure 8-5.

REF80

SNAS856 – SEPTEMBER 2024

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