THS4531A_16 Datasheet, PDF (33/59 Pages) Texas Instruments – Ultra Low-Power, Rail-to-Rail Output, Fully Differential Amplifier

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THS4531A
SLOS823C – DECEMBER 2012 – REVISED JANUARY 2016
9.1.10 Audio Performance
The THS4531A provides excellent audio performance with very low quiescent power. To show performance in
the audio band, the device was tested with an audio analyzer. THD+N and FFT tests were run at 1-Vrms output
voltage. Performance is the same on both 2.7-V and 5-V supply. Figure 79 is the test circuit used, and Figure 80
and Figure 81 show performance of the analyzer. In the FFT plot the harmonic spurs are at the testing limit of the
analyzer, which means the THS4531A is actually much better than can be directly measured. Because the
THS4531A distortion performance cannot be directly measured in the audio band it is estimated from
measurement in high noise gain configuration correlated with simulation.
V_IN±
R_G
100 pF
R_F
10
V_OUT±
V_S+
From Analyzer
0.22 F
+
V_OCM
±
THS4531A
To Analyzer
V_IN+
R_G
10
V_OUT+
100 pF
R_F
Figure 79. THS4531A Audio Analyzer Test Circuit
−95
−97
−99
−101
−103
No Weighting
A−Weighting
V_S = 5 V
G = 1 V/V
V_OUT = 1 V_RMS
R_F = 2 kΩ
R_L = 600 Ω
−105
−107
−109
−111
−113
−115
0
5k
10k
15k
20k
24k
Frequency (Hz)
G070
Figure 80. THD+N on Audio Analyzer, 10 Hz to 24 kHz
0
−10
V_S = 5 V
−20
G = 1 V/V
−30
V_OUT = 1 V_RMS
−40
R_F = 2 kΩ
−50
R_L = 600 Ω
−60
−70
−80
−90
−100
−110
−120
−130
−140
0
5k
10k
15k
20k
24k
Frequency (Hz)
G071
Figure 81. 1-kHz FFT Plot on Audio Analyzer
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