THS4531 Datasheet, PDF (39/55 Pages) Texas Instruments – Ultra Low Power, Rail-to-Rail Output, Fully-Differential Amplifier

THS4531
www.ti.com
SLOS358B – SEPTEMBER 2011 – REVISED MARCH 2012
An audio analyzer is used to provide an analog audio input to the EVM and the PCM formatted digital output is
read by the digital input on the analyzer. Data was taken at f_S = 96kHz, and audio output uses PCM format.
Other data rates and formats are expected to show similar performance in line with that shown in the data sheet.
Figure 87 shows the THD+N vs Frequency with no weighting and Figure 88 shows an FFT with 1kHz input tone.
Input signal to the PCM4204 for these tests is -0.5dBFS. Table 4 summarizes results of testing using the
THS4531 + PCM4204 versus typical Data Sheet performance, and show it make an excellent drive amplifier for
this ADC.
−95
−97
−99
−101
−103
−105
−107
−109
−111
−113
−115
20
100
1k
Frequency (Hz)
10k 20k
G075
Figure 87. THS4531 + PCM4204 THD+N vs Frequency with No Weighting
0
−10
−20
−30
−40
−50
−60
−70
−80
−90
−100
−110
−120
−130
−140
−150
20
100
1k
Frequency (Hz)
10k 24k
G076
Figure 88. THS4531 + PCM4204 1kHz FFT
Table 4. 1kHz AC Analysis: Test Circuit versus PCM4204 Data Sheet Typical Specifications (f_S = 96kSPS)
CONFIGURATION
TONE
THD + N
THS4531 + PCM4204
1kHz
-106 dB
PCM4204 Data Sheet (typ)
1kHz
-103 dB
SAR ADC PERFORMANCE
THS4531 and ADS8321 Combined Performance
To show achievable performance with a high performance SAR ADC, the THS4531 is tested as the drive
amplifier for the ADS8321. The ADS8321 is a 16-bit, SAR ADC that offers excellent AC and DC performance,
with ultra-low power and small size. The circuit shown in Figure 89 is used to test the performance. Data was
taken using the ADS8321 at 100kSPS with input frequency of 10 kHz and signal levels 0.5 dB below full scale.
The FFT plot of the spectral performance is in Figure 90. A summary of the FFT analysis results are in Table 5
along with ADS8321 typical data sheet performance at f_S = 100kSPS. Please refer to its data sheet for more
information.
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