EVAL-AD7723CBZ Analog Devices Inc, EVAL-AD7723CBZ Datasheet - Page 19

• Manufacturer Part Number: EVAL-AD7723CBZ
• Description: BOARD EVALUATION FOR AD7723
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD7723CBZ

• Number Of Adc's: 1
• Number Of Bits: 16
• Sampling Rate (per Second): 1.2M
• Data Interface: Serial, Parallel
• Inputs Per Adc: 1 Differential
• Input Range: ±VREF
• Power (typ) @ Conditions: 475mW @ 1.2MSPS
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: AD7723
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

–100dB
–100dB
–100dB
0dB
0dB
0dB
0
0
0
Figure 31. Band-Pass Filter Decimate by 32
Figure 29. Low-Pass Filter Decimate by 16
Figure 30. Low-Pass Filter Decimate by 32
f
f
f
CLKIN
CLKIN
0.5
CLKIN
0.5
0.5
1.0
1.0
1.0
Rev. C | Page 19 of 32
Figure 32 shows the frequency response of the digital filter in
both low-pass and band-pass modes. Due to the sampling
nature of the converter, the pass-band response is repeated
about the input sampling frequency, f
multiples of f
any of the filter images are aliased down to the pass band.
However, due to the AD7723’s high oversampling ratio, these
bands occupy only a small fraction of the spectrum, and most
broadband noise is attenuated by at least 90 dB. In addition, as
shown in Figure 33, with even a low-order filter, there is
significant attenuation at the first image frequency. This
contrasts with a normal Nyquist rate converter where a very
high-order antialias filter is required to allow most of the
bandwidth to be used while ensuring sufficient attenuation at
multiples of f
0dB
0dB
DATA RATE
OUTPUT
f
CLKIN
Figure 33. Frequency Response of Antialias Filter
CLKIN
CLKIN
Figure 32. Digital Filter Frequency Response
/32
. Out-of-band noise or signals coincident with
.
1
f
CLKIN
ANTIALIAS FILTER
RESPONSE
2
f
CLKIN
CLKIN
f
CLKIN
, and at integer
3
f
CLKIN
REQUIRED
ATTENUATION
AD7723