Datasheet

−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
2 k
2 k
0.22 F
5 V
THS4531A
V
OUT+
40.2 
V
OUT±
40.2 
Differential
Signal from
Generator and
10 kHz BPF
V
IN+
V
IN±
+
±
V
OCM
2 k
1 nF
2 k
To Data
Analysis
ADS7945
100 pF
100 pF
THS4531A
SLOS823A –DECEMBER 2012–REVISED JANUARY 2013 www.ti.com
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.
Figure 93. THS4531A and ADS7945 Test Circuit
Figure 94. THS4531A and ADS7945 Test Circuit
Table 6. 10kHz FFT Analysis Summary
CONFIGURATION TONE SIGNAL SNR THD SFDR
THS4531A + 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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