Datasheet

0
-1
-2
-3
-4
-5
-6
-7
-8
-9
-10
NormalizedInputFrequency(f /f
IN TDA A
)
Amplitude(dB)
0.45 0.47 0.49 0.51 0.53 0.55
0
-20
-40
-60
-80
-100
-120
-140
0.50
NormalizedInputFrequency(f
IN
/f
DATA
)
Amplitude(dB)
0 0.25 0.75 1
20
0
-20
-40
-60
-80
-100
-120
-140
-160
Gain(dB)
NormalizedInputFrequency(f /f
IN DATA
)
0 32 64 96 128
0.02
0
-0.02
-0.04
-0.06
-0.08
-0.10
0.2
NormalizedInputFrequency(f /f
IN DATA
)
Amplitude(dB)
0 0.1 0.3 0.4 0.5 0.6
ADS1274
ADS1278
www.ti.com SBAS367F –JUNE 2007– REVISED FEBRUARY 2011
High-Resolution Mode
The oversampling ratio is 128 in High-Resolution
mode. Figure 62 shows the frequency response in
High-Resolution mode normalized to f
DATA
. Figure 63
shows the passband ripple, and the transition from
passband to stop band is shown in Figure 64. The
overall frequency response repeats at multiples of the
modulator frequency f
MOD
(128 × f
DATA
), as shown in
Figure 65. The stop band of the ADS1274/78
provides 100dB attenuation of frequencies that begin
just beyond the passband and continue out to f
MOD
.
Placing an antialiasing, low-pass filter in front of the
ADS1274/78 inputs is recommended to limit possible
high-amplitude out-of-band signals and noise. Often,
a simple RC filter is sufficient. Table 4 lists the image
rejection versus external filter order.
Figure 64. Transition Band Response for
High-Resolution mode
Figure 62. Frequency Response for
High-Resolution Mode
Figure 65. Frequency Response Out to f
MOD
for
High-Resolution Mode
Figure 63. Passband Response for
High-Resolution Mode
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Product Folder Link(s): ADS1274 ADS1278