Flicker Noise (ppmp-p)

0

20

40

60

80

100

0

0.04 0.08 0.12 0.16

0.2

0.24 0.28 0.32

0.4

Figure 7-5. 0.1-Hz to 10-Hz Voltage Noise (NR = 100 μF)

7.3.2 Broadband Noise

Broadband noise or white noise is flat over the whole spectrum which is restricted by the bandwidth of internal

bandgap reference. The broadband noise is measured by high-pass filtering the output of the REF54 and

measuring the result on a precision spectrum analyzer as shown in Figure 7-6. The DC component of the REF54

is removed by using a high-pass filter and then amplified. Two stages of small gain has been used to maximize

the noise bandwidth analysis.

REF54

GND

OUTF

VIN

EN

VIN

CL

CIN

VREFP

NR

CNR

Spectrum

Analyzer

Post Amplifier

G = 11

High-pass Filter

G = 11

Figure 7-6. Broadband Noise Test Setup

Figure 7-7 shows the typical white noise floor for REF54. Designer can use NR pin to restrict the noise

bandwidth to achieve required resolution for the signal chain.

Frequency (Hz)

101

102

103

104

105

0

20

40

60

80

100

1uF

10uF

100uF

Figure 7-7. Noise Performance 10 Hz to 100 kHz (NR = 0 μF)

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REF54

SNVSCN7 – NOVEMBER 2023

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Product Folder Links: REF54