THS4531A Datasheet, PDF (38/50 Pages) Texas Instruments – Ultra Low Power, Rail-to-Rail Output, Fully-Differential Amplifier

THS4531A
SLOS823A – DECEMBER 2012 – REVISED JANUARY 2013
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The standard ADS7945 EVM and THS4531A EVM are modified to implement the schematic in Figure 93 and
used to test the performance of the THS4531A as a drive amplifier. With single supply +5V supply the output
common-mode of the THS4531A defaults to +2.5V as required at the input of the ADS7945 so the V_OCM input of
the THS4531A simply bypassed to GND with 0.22µF capacitor. The summary of results of the FFT analysis
versus typical data sheet performance shown in Table 6 show the THS4531A will make an excellent drive
amplifier for this ADC.
V_IN±
Differential
Signal from
Generator and
10 kHz BPF
2k
100 pF
0.22 F
2k
40.2
5V
V_OUT±
+
V_OCM
±
THS4531A 1 nF
V_OUT+
ADS7945
To Data
Analysis
2k
2k
40.2
V_IN+
100 pF
CONFIGURATION
THS4531A + ADS7945
ADS7945 Data Sheet (typ)
Figure 93. THS4531A and ADS7945 Test Circuit
0
−10
−20
−30
−40
−50
−60
−70
−80
−90
−100
−110
−120
−130
−140
1k
V_S = 5 V
G = 1 V/V
R_F = 2 kΩ
V_OUT = −0.5 dBFS
10k
100k
Frequency (Hz)
1M
G077
Figure 94. THS4531A and ADS7945 Test Circuit
Table 6. 10kHz FFT Analysis Summary
TONE
10kHz
10kHz
SIGNAL
-0.5 dBFS
-0.5 dBFS
SNR
83 dBc
84 dBc
THD
-93 dBc
-92 dBc
SFDR
96 dBc
94 dBc
38
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