High-pass Filter

FC = 0.07Hz

REF54

GND

VREF

VIN

EN

VIN

CL

CIN

VREF

Low Noise

Preamplifier

G = 1000

2

nd Order

Low-pass Filter

FC = 10Hz

G = 1

2

nd Order

Low-pass Filter

FC = 10Hz

G = 10

2

nd Order

High-pass Filter

FC = 0.1Hz

G = 10

Scope

NR

CNR

Figure 7-6. 1/f Noise Test Setup

Figure 7-7 shows typical distribution of flicker noise for multiple devices where more than 1000 samples have

been captured for each device.

Flicker Noise (ppmp-p)

0

20

40

60

80

100

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Figure 7-7. 0.1Hz to 10Hz Voltage Noise Distribution (CNR = Open)

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 14kΩ. 100μF capacitor on NR pin

removes the whole band of flicker noise (0.1Hz) from the band gap reference as shown in Figure 7-8. A 10μF

capacitor on the NR pin creates a 1Hz low-pass filter for the bandgap.

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REF54

SNVSCN7D – NOVEMBER 2023 – REVISED JUNE 2026

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