Texas Instruments DRV600EVM, Руководство пользователя, Страница: 8 / 16

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10
1
0.1
THD+N(%)
0.01
0.001
20 100 1k
Frequency (Hz)
10k 20k
Left
Right
4.3.1 FFT Spectrum with –60dBFS Tone
0
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10
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20
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150
OutputV
oltage(dBrA)
0 2k
Frequency (Hz)
22k 4k 6k 8k 10k 12k 14k 16k 18k 20k
DRV600EVM Performance
The DRV600EVM uses a 1 μ F film capacitor for ac-coupling of the input signal. If a lower cost ceramic
capacitor such as an X7R is used, higher THD at low frequencies should be expected. Y5V capacitors will
show even higher THD performance and should not be used.
Figure 8. THD+N vs Frequency (600
Ω
load) Using X7R Input Caps
The X7R capacitors raises the 20Hz THD from 0.02% to 0.1%—five times higher.
Reference voltage is 2V
RMS
, FFT size 16k.
Figure 9. FFT Spectrum with –60dBFS Tone
This spectrum corresponds to a dynamic range of 110dB, A-weighted. SNR measures at 110dB,
A-weighted.
DRV600EVM User's Guide 8 SLOU205 – July 2007
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