THS4531 Datasheet, PDF (41/54 Pages) Texas Instruments – Ultra Low Power, Rail-to-Rail Output, Fully-Differential Amplifier

THS4531
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SLOS358B – SEPTEMBER 2011 – REVISED MARCH 2012
The standard ADS7945 EVM and THS4531 EVM are modified to implement the schematic in Figure 91 and used
to test the performance of the THS4531 as a drive amplifier. With single supply +5V supply the output common-
mode of the THS4531 defaults to +2.5V as required at the input of the ADS7945 so the V_OCM input of the
THS4531 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 THS4531 will make an excellent drive amplifier for
this ADC.
V_IN–
Differential
Signal from
Generator and
10 kHz BPF
V_IN+
2 kȍ
100 pF
0.22 ȝF
2 kȍ
100 pF
2 kȍ
40.2 ȍ
5V
V_OUT–
+
V_OCM
–
THS4531
V_OUT+
1 nF
2 kȍ
40.2 ȍ
ADS7945
To Data
Analysis
CONFIGURATION
THS4531 + ADS7945
ADS7945 Data Sheet (typ)
Figure 91. THS4531 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 92. THS4531 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
Copyright © 2011–2012, Texas Instruments Incorporated
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