Datasheet

2 kȍ
2 kȍ
0.22 ȝF
5 V
THS4531
V
OUT+
40.2 ȍ
V
OUT–
40.2 ȍ
Differential
Signal from
Generator and
10 kHz BPF
V
IN+
V
IN–
+
–
V
OCM
2 kȍ
1 nF
2 kȍ
To Data
Analysis
ADS7945
100 pF
100 pF
−140
−130
−120
−110
−100
−90
−80
−70
−60
−50
−40
−30
−20
−10
0
1k 10k 100k 1M
Frequency (Hz)
Magnitude (dBFS)
V
S
= 5 V
G = 1 V/V
R
F
= 2 kΩ
V
OUT
= −0.5 dBFS
G077
THS4531
www.ti.com 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.
Figure 91. THS4531 and ADS7945 Test Circuit
Figure 92. THS4531 and ADS7945 Test Circuit
Table 6. 10kHz FFT Analysis Summary
CONFIGURATION TONE SIGNAL SNR THD SFDR
THS4531 + ADS7945 10kHz -0.5 dBFS 83 dBc -93 dBc 96 dBc
ADS7945 Data Sheet (typ) 10kHz -0.5 dBFS 84 dBc -92 dBc 94 dBc
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