adv7314 Analog Devices, Inc., adv7314 Datasheet - Page 56

• Manufacturer Part Number: adv7314
• Description: Multiformat 216 Mhz Video Encoder With Six Nsv 14-bit Dacs
• Manufacturer: Analog Devices, Inc.

ADV7314
BOARD DESIGN AND LAYOUT CONSIDERATIONS
DAC Termination and Layout Considerations
The ADV7314 contains an on-board voltage reference. The
ADV7314 can be used with an external V
The R
AGND and are used to control the full-scale output current and
therefore the DAC voltage output levels. For full-scale output,
R
be changed. R
for full-scale output.
Video Output Buffer and Optional Output Filter
Output buffering on all six DACs is necessary in order to drive
output devices, such as SD or HD monitors. Analog Devices
produces a range of suitable op amps for this application, for
example the AD8061. More information on line driver buffering
circuits is given in the relevant op amp data sheets.
An optional analog reconstruction low-pass filter (LPF) may be
required as an anti-imaging filter if the ADV7314 is connected
to a device that requires this filtering. The filter specifications
vary with the application.
Application Oversampling (MHz)
SD
SD
PS
PS
HDTV
HDTV
SET
must have a value of 3040 W. The R
SET
resistors are connected between the R
Table XVI. External Filter Requirements
LOAD
2¥
16¥
1¥
8¥
1¥
2¥
has a value of 150 W with a 4 gain stage
Cutoff
Frequency Attenuation
>6.5
>6.5
>12.5
>12.5
>30
>30
REF
SET
(AD1580).
values should not
–50 dB @ (MHz)
20.5
209.5
14.5
203.5
44.25
118.5
SET
pins and
–56–
DAC OUTPUT
–10
–15
–20
–25
–30
–35
–40
Figure 54. Example for Output Filter for SD,
16
Figure 55. Filter Plot for Output Filter for SD,
16
–5
0
1M
300
Oversampling
Oversampling
2.2 H
22pF
CIRCUIT FREQUENCY RESPONSE
GROUP DELAY (sec)
300
FREQUENCY (Hz)
10M
PHASE (Deg)
600
3
4
1.8k
MAGNITUDE (dB)
1
100M
75
BNC OUTPUT
0
–30
–60
–90
–120
–150
–180
–210
–240
REV. 0
16n
14n
12n
10n
8n
6n
4n
2n
0