Document Outline
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Integrated Triple Video Filter with Selectable
Cutoff Frequencies for RGB, HD/SD
ADA4412-3
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
© 2005 Analog Devices, Inc. All rights reserved.
FEATURES
Sixth-order adjustable video filters
36 MHz, 18 MHz, and 9 MHz
Many video standards supported: RGB, YPbPr, YUV, SD, Y/C
Ideal for 720p and 1080i resolutions
-1 dB bandwidth of 31.5 MHz for HD
Low quiescent power
Only 265 mW for 3 channels on 5 V supply
Disable feature cuts supply current to 10 A
DC output offset adjust: ±0.5 V, input referred
Fixed throughput gain of ×2
Excellent video specifications
Wide supply range: +4.5 V to ±5 V
Rail-to-rail output
Output can swing 4.5 V p-p on single 5 V supply
Small packaging: 20-lead QSOP
APPLICATIONS
Set-top boxes
DVD players and recorders
Personal video recorders
HDTVs
Projectors
FUNCTIONAL BLOCK DIAGRAM
0
5528-
001
CUTOFF SELECT
DC
OFFSET
LEVEL2
LEVEL1
2
Y/G OUT
Pb/B OUT
Pr/R OUT
DISABLE
Y/G IN
Pb/B IN
Pr/R IN
36MHz, 18MHz, 9MHz
36MHz, 18MHz, 9MHz
36MHz, 18MHz, 9MHz
×2
×2
×2
×1
×1
×1
ADA4412-3
Figure 1.
GENERAL DESCRIPTION
The ADA4412-3 is a comprehensive filtering solution designed
to give designers the flexibility to easily filter and drive various
video signals, including high definition video. Cutoff frequen-
cies of the sixth-order video filters range from 9 MHz to
36 MHz and can be selected by two logic pins to obtain four
filter combinations that are tuned for RGB, high definition, and
standard definition video signals. The ADA4412-3 has a rail-to-
rail output that can swing 4.5 V p-p on a single 5 V supply.
The ADA4412-3 includes an output offset voltage adjustment
feature. Output voltage offset is continuously adjustable over an
input-referred range of ±500 mV by applying a differential
voltage to an independent offset control input.
The ADA4412-3 can operate on a single +5 V supply as
well as on ±5 V supplies. Single-supply operation is ideal in
applications where power consumption is critical. The disable
feature allows for further power conservation by reducing the
supply current to typically 10 A when a particular device is not
in use.
Dual-supply operation is best for applications where the
negative-going video signal excursions must swing at or below
ground while maintaining excellent video performance. The
output buffers have the ability to drive two 75 doubly
terminated cables that are either dc-coupled or ac-coupled.
The ADA4412-3 is available in a 20-lead QSOP and is rated for
operation over the extended industrial temperature range of
-40°C to +85°C.
ADA4412-3
Rev. 0 | Page 2 of 16
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 5
Thermal Resistance ...................................................................... 5
ESD Caution.................................................................................. 5
Pin Configuration And Function Descriptions............................ 6
Typical Performance Characteristics ............................................. 7
Theory of Operation ........................................................................ 9
Applications..................................................................................... 10
Overview ..................................................................................... 10
Disable ......................................................................................... 10
Cutoff Frequency Selection....................................................... 10
Output DC Offset Control ........................................................ 10
Input and Output Coupling ...................................................... 11
Printed Circuit Board Layout ................................................... 11
Video Encoder Reconstruction Filter...................................... 11
Outline Dimensions ....................................................................... 13
Ordering Guide .......................................................................... 13
REVISION HISTORY
7/05--Revision 0: Initial Version
ADA4412-3
Rev. 0 | Page 3 of 16
SPECIFICATIONS
V
S
= 5 V, @ T
A
= 25°C, V
O
= 1.4 V p-p, R
L
= 150 , unless otherwise noted.
Table 1.
Parameter Test
Conditions/Comments
Min
Typ
Max
Unit
OVERALL
PERFORMANCE
Offset Error
Input referred, all channels
9
23
mV
Offset Adjust Range
Input referred
±500
mV
Input Voltage Range, All Inputs
V
S-
- 0.1
V
S+
- 2.0
V
Output Voltage Swing, All Outputs
Positive swing
V
S+
- 0.30
V
S+
- 0.20
V
Negative
swing
V
S-
+ 0.10
V
S-
+ 0.15
V
Linear Output Current per Channel
30
mA
Integrated Voltage Noise, Referred to Input
All channels
0.50
mV rms
Filter Input Bias Current
All channels
6.6
A
Total Harmonic Distortion at 1 MHz
F
C
= 36 MHz, F
C
= 18 MHz/F
C
= 9 MHz
0.01/0.04
%
Gain Error Magnitude
0.09
0.49
dB
FILTER DYNAMIC PERFORMANCE
-1 dB Bandwidth
Cutoff frequency select = 36 MHz
26.5
31.5
MHz
Cutoff frequency select = 18 MHz
13.5
15.5
MHz
Cutoff frequency select = 9 MHz
6.5
8.0
MHz
-3 dB Bandwidth
Cutoff frequency select = 36 MHz
34
37
MHz
Cutoff frequency select = 18 MHz
16
19
MHz
Cutoff frequency select = 9 MHz
8
9
MHz
Out-of-Band Rejection
f = 75 MHz
-31
-43
dB
Crosstalk
f = 5 MHz, F
C
= 36 MHz
-62
dB
Propagation Delay
f = 5 MHz, F
C
= 36 MHz
19
ns
Group Delay Variation
Cutoff frequency select = 36 MHz
7
ns
Cutoff frequency select = 18 MHz
14
ns
Cutoff frequency select = 9 MHz
27
ns
Differential Gain
NTSC, F
C
= 9 MHz
0.16
%
Differential Phase
NTSC, F
C
= 9 MHz
0.05
Degrees
CUTOFF CONTROL INPUT PERFORMANCE
Input Logic 0 Voltage
0.8
V
Input Logic 1 Voltage
2.0
V
Input Bias Current
10
15
A
DISABLE
PERFORMANCE
DISABLE Assert Voltage
V
S+
- 0.5
V
DISABLE Assert Time
100
ns
DISABLE Deassert Time
130
ns
DISABLE Input Bias Current
12
A
Input-to-Output Isolation--Disabled
f = 10 MHz
90
dB
POWER
SUPPLY
Operating Range
4.5
12
V
Quiescent
Current
53 56 mA
Quiescent Current--Disabled
10
150
A
PSRR, Positive Supply
All channels
64
70
dB
PSRR, Negative Supply
All channels
58
60
dB
ADA4412-3
Rev. 0 | Page 4 of 16
V
S
= ±5 V, @ T
A
= 25°C, V
O
= 1.4 V p-p, R
L
= 150 , unless otherwise noted.
Table 2.
Parameter Test
Conditions/Comments
Min
Typ
Max
Unit
OVERALL
PERFORMANCE
Offset Error
Input referred, all channels
10
25
mV
Offset Adjust Range
Input referred
±500
mV
Input Voltage Range, All Inputs
V
S-
- 0.1
V
S+
- 2.0
V
Output Voltage Swing, All Outputs
Positive swing
V
S+
- 0.33
V
S+
- 0.24
V
Negative
swing
V
S-
+ 0.24
V
S-
+ 0.33
V
Linear Output Current per Channel
30
mA
Integrated Voltage Noise, Referred to Input
All channels
0.50
mV rms
Filter Input Bias Current
All channels
6.3
A
Total Harmonic Distortion at 1 MHz
F
C
= 36 MHz, F
C
= 18 MHz/F
C
= 9 MHz
0.01/0.03
%
Gain Error Magnitude
0.04
0.50
dB
FILTER DYNAMIC PERFORMANCE
-1 dB Bandwidth
Cutoff frequency select = 36 MHz
30.0
MHz
Cutoff frequency select = 18 MHz
15.5
MHz
Cutoff frequency select = 9 MHz
8.0
MHz
-3 dB Bandwidth
Cutoff frequency select = 36 MHz
34
36
MHz
Cutoff frequency select = 18 MHz
17
19
MHz
Cutoff frequency select = 9 MHz
8
9
MHz
Out-of-Band Rejection
f = 75 MHz
-31
-42
dB
Crosstalk
f = 5 MHz, F
C
= 36 MHz
-62
dB
Propagation Delay
f = 5 MHz, F
C
= 36 MHz
19
ns
Group Delay Variation
Cutoff frequency select = 36 MHz
7
ns
Cutoff frequency select = 18 MHz
12
ns
Cutoff frequency select = 9 MHz
24
ns
Differential Gain
NTSC, F
C
= 9 MHz
0.04
%
Differential Phase
NTSC, F
C
= 9 MHz
0.16
Degrees
CUTOFF CONTROL INPUT PERFORMANCE
Input Logic 0 Voltage
0.8
V
Input Logic 1 Voltage
2.0
V
Input Bias Current
10
15
A
DISABLE
PERFORMANCE
DISABLE Assert Voltage
V
S+
- 0.5
V
DISABLE Assert Time
75
ns
DISABLE Deassert Time
125
ns
DISABLE Input Bias Current
35
A
Input-to-Output Isolation--Disabled
f = 10 MHz
90
dB
POWER
SUPPLY
Operating Range
4.5
12
V
Quiescent
Current
57 60 mA
Quiescent Current--Disabled
10
150
A
PSRR, Positive Supply
All channels
66
74
dB
PSRR, Negative Supply
All channels
59
62
dB
ADA4412-3
Rev. 0 | Page 5 of 16
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Rating
Supply Voltage
12 V
Power Dissipation
See Figure 2
Storage Temperature
65°C to +125°C
Operating Temperature Range
40°C to +85°C
Lead Temperature Range (Soldering 10 sec)
300°C
Junction Temperature
150°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
THERMAL RESISTANCE
JA
is specified for the worst-case conditions, that is,
JA
is
specified for device soldered in circuit board for surface-mount
packages.
Table 4. Thermal Resistance
Package Type
JA
Unit
20-Lead QSOP
83
°C/W
Maximum Power Dissipation
The maximum safe power dissipation in the ADA4412-3
package is limited by the associated rise in junction temperature
(T
J
) on the die. At approximately 150°C, which is the glass
transition temperature, the plastic changes its properties.
Even temporarily exceeding this temperature limit may change
the stresses that the package exerts on the die, permanently
shifting the parametric performance of the ADA4412-3.
Exceeding a junction temperature of 150°C for an extended
period can result in changes in the silicon devices potentially
causing failure.
The power dissipated in the package (P
D
) is the sum of the
quiescent power dissipation and the power dissipated in the
package due to the load drive for all outputs. The quiescent
power is the voltage between the supply pins (V
S
) times the
quiescent current (I
S
). The power dissipated due to load drive
depends on the particular application. For each output, the
power due to load drive is calculated by multiplying the load
current by the associated voltage drop across the device. The
power dissipated due to all of the loads is equal to the sum of
the power dissipations due to each individual load. RMS
voltages and currents must be used in these calculations.
Airflow increases heat dissipation, effectively reducing
JA
.
In addition, more metal directly in contact with the package
leads from metal traces, through-holes, ground, and power
planes reduces the
JA
.
Figure 2 shows the maximum safe power dissipation in the
package vs. the ambient temperature for the 20-lead QSOP
(83°C/W) on a JEDEC standard 4-layer board.
JA
values are
approximations.
05
52
8-
0
02
AMBIENT TEMPERATURE (
°
C)
WA
TTS
40
20
0
20
40
60
0.5
0.7
0.9
1.1
1.3
1.5
1.7
1.9
2.1
2.3
2.5
80
Figure 2. Maximum Power Dissipation vs. Temperature for a 4-Layer Board
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
ADA4412-3
Rev. 0 | Page 6 of 16
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
0552
8-
003
1
2
3
4
5
6
7
8
9
10
16
17
18
19
20
15
14
13
12
11
DISABLE
Y/G
GND
Pr/R
GND
Pb/B
LEVEL1
VCC
Y/G_OUT
VEE
Pr/R_OUT
VEE
Pb/B_OUT
F_SEL_A
F_SEL_B
GND
VCC
NC
DGND
NC = NO CONNECT
LEVEL2
ADA4412-3
TOP VIEW
(Not to Scale)
Figure 3. 20-Lead QSOP Pin Configuration
Table 5. 20-Lead QSOP Pin Function Descriptions
Pin No.
Name
Description
1
LEVEL1
DC Level Adjust Pin 1
2 DISABLE Disable/Power
Down
3 Y/G
Y/G
Video
Input
4
GND
Signal Ground Reference
5 Pb/B
Pb/B
Video
Input
6
GND
Signal Ground Reference
7 Pr/R
Pr/R
Video
Input
8
F_SEL_A
Filter Cutoff Select Input A
9
F_SEL_B
Filter Cutoff Select Input B
10
GND
Signal Ground Reference
11
DGND
Digital Ground Reference
12
NC
No Internal Connection
13
VCC
Positive Power Supply
14 Pr/R_OUT Pr/R
Video
Output
15 VEE
Negative
Power
Supply
16 Pb/B_OUT Pb/B
Video
Output
17 VEE
Negative
Power
Supply
18 Y/G_OUT Y/G
Video
Output
19
VCC
Positive Power Supply
20
LEVEL2
DC Level Adjust Pin 2
ADA4412-3
Rev. 0 | Page 7 of 16
TYPICAL PERFORMANCE CHARACTERISTICS
Unless otherwise noted, R
L
= 150 , V
O
= 1.4 V p-p, V
S
= 5 V, T
A
= 25°C.
0552
8-
004
FREQUENCY (MHz)
GA
IN
(
d
B
)
1
10
100
48
45
42
39
36
33
30
27
24
21
18
15
12
9
6
3
0
3
6
9
F
C
= 9MHz
F
C
= 18MHz
F
C
= 36MHz
BLACK LINE: V
S
= +5V
GRAY LINE: V
S
= ±5V
Figure 4. Frequency Response vs. Power Supply and Cutoff Frequency
0552
8-
005
FREQUENCY (MHz)
GA
IN
(
d
B
)
1
10
100
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
BLACK LINE: V
S
= +5V
GRAY LINE: V
S
= ±5V
F
C
= 9MHz
F
C
= 18MHz
F
C
= 36MHz
Figure 5. Frequency Response Flatness vs. Cutoff Frequency
055
28-
006
FREQUENCY (MHz)
GA
IN
(
d
B
)
1
10
100
48
45
42
39
36
33
30
27
24
21
18
15
12
9
6
3
0
3
6
9
F
C
= 9MHz
F
C
= 18MHz
F
C
= 36MHz
BLACK LINE:
V
OUT
= 100mV p-p
GRAY LINE:
V
OUT
= 2V p-p
Figure 6. Frequency Response vs. Output Amplitude and Cutoff Frequency
0552
8-
007
FREQUENCY (MHz)
GA
IN
(
d
B
)
1
10
100
48
45
42
39
36
33
30
27
24
21
18
15
12
9
6
3
0
3
6
9
F
C
= 36MHz
F
C
= 9MHz
F
C
= 18MHz
40
°
C
+25
°
C
+85
°
C
Figure 7. Frequency Response vs. Temperature and Cutoff Frequency
0552
7-
008
FREQUENCY (MHz)
GR
OU
P
D
E
LA
Y
(
n
s
)
1
10
10
100
90
80
70
60
50
40
30
20
100
F
C
= 9MHz
F
C
= 18MHz
F
C
= 36MHz
BLACK LINE: V
S
= +5V
GRAY LINE: V
S
= ±5V
Figure 8. Group Delay vs. Frequency, Power Supply, and Cutoff Frequency
055
28-
009
FREQUENCY (MHz)
C
RO
S
S
T
AL
K RE
F
E
RR
E
D
T
O
I
NP
UT
(
d
B
)
0.1
1
10
100
100
90
80
70
60
50
40
F
C
= 9MHz
F
C
= 18MHz
F
C
= 36MHz
R
SOURCE
= 300
Y AND Pr SOURCE CHANNELS
Pb RECEPTOR CHANNEL
Figure 9. Channel-to-Channel Crosstalk vs. Frequency and Cutoff Frequency
ADA4412-3
Rev. 0 | Page 8 of 16
0552
8-
011
FREQUENCY (MHz)
P
S
RR (
d
B
)
0.1
1
10
100
75
65
55
45
35
25
15
5
5
F
C
= 9MHz
F
C
= 18MHz
F
C
= 36MHz
Figure 10. Positive Supply PSRR vs. Frequency and Cutoff Frequency
05
52
8-
0
10
O
U
TP
U
T
V
O
LTA
GE
(
V
)
E
RRO
R (
%
)
1.5
1.7
1.9
2.1
2.3
2.5
2.7
2.9
3.1
3.3
3.5
2.5
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.5
50ns/DIV
2 ×
INPUT
OUTPUT
0.5% (70ns)
ERROR
1% (58ns)
Figure 11. Settling Time
05528-
012
O
U
TP
U
T
V
O
LTA
G
E
(
V
)
1.5
1.7
1.9
2.1
2.3
2.5
2.7
2.9
3.1
3.3
3.5
100ns/DIV
F
C
= 9MHz
F
C
= 18MHz
F
C
= 36MHz
Figure 12. Transient Response vs. Cutoff Frequency
0552
8-
013
FREQUENCY (MHz)
P
S
RR (
d
B
)
0.1
1
10
100
75
5
5
15
25
35
45
55
65
F
C
= 9MHz
F
C
= 18MHz
F
C
= 36MHz
Figure 13. Negative Supply PSRR vs. Frequency and Cutoff Frequency
05528-
014
O
U
TP
U
T
V
O
LTA
G
E
(
V
)
1
6
5
4
3
2
1
0
200ns/DIV
2
×
INPUT
F
C
= 36MHz
F
C
= 18MHz
F
C
= 9MHz
Figure 14. Overdrive Recovery vs. Cutoff Frequency
05528
-
051
MINIMUM-LOSS MATCHING NETWORK LOSS CALIBRATED OUT
50
118
R
L
= 150
50
86.6
50
NETWORK
ANALYZER Tx
NETWORK
ANALYZER Rx
DUT
Figure 15. Basic Test Circuit for Swept Frequency Measurements
ADA4412-3
Rev. 0 | Page 9 of 16
THEORY OF OPERATION
The ADA4412-3 is an integrated video filtering and driving
solution that offers variable bandwidth to meet the needs of a
number of different video resolutions. There are three filters
targeted for use with component video signals. The filters
have selectable bandwidths that correspond to the popular
component video standards. Each filter has a sixth-order
Butterworth response that includes group delay optimization.
The group delay variation from 1 MHz to 36 MHz in the
36 MHz section is 7 ns, which produces a fast settling pulse
response.
The ADA4412-3 is designed to operate in many video environ-
ments. The supply range is 5 V to 12 V, single supply or dual
supply, and requires a relatively low nominal quiescent current
of 15 mA per channel. In single-supply applications, the PSRR
is greater than 60 dB, providing excellent rejection in systems
with supplies that are noisy or under-regulated. In applications
where power consumption is critical, the part can be powered
down to draw typically 10 A by pulling the DISABLE pin to
the most positive rail. The ADA4412-3 is also well-suited for
high encoding frequency applications because it maintains a
stop-band attenuation of over 40 dB to 400 MHz.
The ADA4412-3 is intended to take dc-coupled inputs
from an encoder or other ground referenced video signals.
The ADA4412-3 input is high impedance. No minimum or
maximum input termination is required, though input
terminations above 1 k can degrade crosstalk performance
at high frequencies. No clamping is provided internally. For
applications where dc restoration is required, dual supplies
work best. Using a termination resistance of less than a few
hundred ohms to ground on the inputs and suitably adjusting
the level-shifting circuitry provides precise placement of the
output voltage.
For single-supply applications (V
S-
= GND), the input voltage
range extends from 100 mV below ground to within 2.0 V of
the most positive supply. Each filter input includes level-shifting
circuitry. The level-shifting circuitry adds a dc component to
ground-referenced input signals so that they can be reproduced
accurately without the output buffers hitting the negative rail.
Because the filters have negative rail input and rail-to-rail
output, dc level shifting is generally not necessary, unless
accuracy greater than that of the saturated output of the driver
is required at the most negative edge. This varies with load but
is typically 100 mV in a dc-coupled, single-supply application. If
ac coupling is used, the saturated output level is higher because
the drivers have to sink more current on the low side. If dual
supplies are used (V
S-
< GND), no level shifting is required. In
dual-supply applications, the level-shifting circuitry can be used
to take a ground referenced signal and put the blanking level at
ground while the sync level is below ground.
The output drivers on the ADA4412-3 have rail-to-rail output
capabilities with 6 dB gain. Each output is capable of driving
two ac- or dc-coupled, 75 source-terminated loads. If a large
dc output level is required while driving two loads, ac coupling
should be used to limit the power dissipation.
ADA4412-3
Rev. 0 | Page 10 of 16
APPLICATIONS
OVERVIEW
With its high impedance inputs and high output drive, the
ADA4412-3 is ideally suited to video reconstruction and
antialias filtering applications. The high impedance inputs give
designers flexibility with regard to how the input signals are
terminated. Devices with DAC current source outputs that feed
the ADA4412-3 can be loaded in whatever resistance provides
the best performance, and devices with voltage outputs can be
optimally terminated as well. The ADA4412-3 outputs can each
drive up to two source-terminated 75 loads and can therefore
directly drive the outputs from set-top boxes, DVD players, and
the like without the need for a separate output buffer.
Binary control inputs are provided to select the filter cutoff
frequency. These inputs are compatible with 3 V and 5 V TTL
and CMOS logic levels referenced to GND. The disable feature
is asserted by pulling the DISABLE pin to the positive supply.
The LEVEL1 and LEVEL2 inputs comprise a differential input
that controls the dc level at the output pins.
DISABLE
The ADA4412-3 includes a disable feature that can be used
to save power when a particular device is not in use. As
indicated in the Overview section, the disable feature is
asserted by pulling the DISABLE pin to the positive supply.
The DISABLE pin also functions as a reference level for the
logic inputs and therefore must be connected to ground when
the device is not disabled.
Table 6 summarizes the disable feature operation.
Table 6. DISABLE Function
DISABLE Pin Connection
Status
V
S+
Disabled
GND Enabled
CUTOFF FREQUENCY SELECTION
Four combinations of cutoff frequencies are provided for the
video signals. The cutoff frequencies have been selected to
correspond with the most commonly deployed component
video scanning systems. Selection between the cutoff frequency
combinations is controlled by the logic signals applied to the
F_SEL_A and F_SEL_B inputs. Table 7 summarizes cutoff
frequency selection.
Table 7. Filter Cutoff Frequency Selection
F_SEL_A
F_SEL_B
Y/G Cutoff
Pb/B Cutoff
Pr/R Cutoff
0
0
36 MHz
36 MHz
36 MHz
0
1
36 MHz
18 MHz
18 MHz
1
0
18 MHz
18 MHz
18 MHz
1
1
9 MHz
9 MHz
9 MHz
OUTPUT DC OFFSET CONTROL
The LEVEL1 and LEVEL2 inputs work as a differential, input-
referred output offset control. In other words, the output offset
voltage of a given channel is equal to the difference in voltage
between the LEVEL1 and LEVEL2 inputs multiplied by the
overall filter gain. This relationship is expressed in Equation 1.
( )
)
(
2
)
(
LEVEL2
LEVEL1
OUT
V
OS
-
=
(1)
LEVEL1 and LEVEL2 are the voltages applied to the respective
inputs, and the factor of 2 reflects the gain of ×2 in the output
stage.
For example, setting LEVEL1 to 300 mV and LEVEL2 to 0 V
shifts the offset voltages at the ADA4412-3 outputs to 600 mV.
This particular setting can be used in most single-supply
applications to keep the output swings safely above the negative
supply rail.
The maximum differential voltage that can be applied across the
LEVEL1 and LEVEL2 inputs is ±500 mV. From a single-ended
standpoint, the LEVEL1 and LEVEL2 inputs have the same
range as the filter inputs. See the Specifications for the limits.
The LEVEL1 and LEVEL2 inputs must each be bypassed to
GND with a 0.1 F ceramic capacitor.
In single-supply applications, a positive output offset must be
applied to keep the negative-most excursions of the output
signals above the specified minimum output swing limit.
Figure 16 and Figure 17 illustrate several ways to use the
LEVEL1 and LEVEL2 inputs. Figure 16 shows examples of how
to generate fully adjustable LEVEL1 and LEVEL2 voltages from
±5 V and single +5 V supplies. These circuits show a general
case, but a more practical approach is to fix one voltage and
vary the other. Figure 17 illustrates an effective way to produce
a 600 mV output offset voltage in a single-supply application.
Although the LEVEL2 input could simply be connected to
GND, Figure 17 includes bypassed resistive voltage dividers for
each input so that the input levels can be changed, if necessary.
Additionally, many in-circuit testers require that I/O signals not
be tied directly to the supplies or GND. DNP indicates do not
populate.
ADA4412-3
Rev. 0 | Page 11 of 16
05
528
-
01
8
DUAL SUPPLY
0.1
F
LEVEL1
9.53k
1k
9.53k
+5V
5V
0.1
F
LEVEL2
9.53k
1k
9.53k
+5V
5V
SINGLE SUPPLY
0.1
F
LEVEL1
1k
9.09k
+5V
0.1
F
LEVEL2
1k
9.09k
+5V
Figure 16. Generating Fully Adjustable Output Offsets
055
28-
01
9
0.1
F
LEVEL1
634
10k
+5V
DNP
LEVEL2
0
DNP
+5V
Figure 17. Flexible Circuits to Set the LEVEL1 and LEVEL2 Inputs to
Obtain a 600 mV Output Offset on a Single Supply
INPUT AND OUTPUT COUPLING
Inputs to the ADA4412-3 are normally dc-coupled. Ac coupling
the inputs is not recommended; however, if ac coupling is
necessary, suitable circuitry must be provided following the ac
coupling element to provide proper dc level and bias currents at
the ADA4412-3 input stages. The ADA4412-3 outputs can be
either ac- or dc-coupled.
When driving single ac-coupled loads in standard 75 video
distribution systems, 220 F coupling capacitors are
recommended for use on all but the chrominance signal output.
Since the chrominance signal is a narrow-band modulated
carrier, it has no low frequency content and can therefore be
coupled with a 0.1 F capacitor.
There are two ac coupling options when driving two loads from
one output. One simply uses the same value capacitor on the
second load, while the other is to use a common coupling
capacitor that is at least twice the value used for the single load
(see Figure 18 and Figure 19).
When driving two parallel 150 loads (75 effective load),
the 3 dB bandwidth of the filters typically varies from that of
the filters with a single 150 load. For the 9 MHz and 18 MHz
filters, the typical variation is within ±1.0%; for the 36 MHz
filters, the typical variation is within ±2.5%.
05
52
8-
02
0
75
ADA4412-3
75
220
F
220
F
75
75
75
CABLE
75
CABLE
Figure 18. Driving Two AC-Coupled Loads with Two Coupling Capacitors
05
528
-
0
21
75
75
75
75
470
F
75
CABLE
75
CABLE
ADA4412-3
Figure 19. Driving Two AC-Coupled Loads with One Common Coupling Capacitor
PRINTED CIRCUIT BOARD LAYOUT
As with all high speed applications, attention to printed
circuit board layout is of paramount importance. Standard high
speed layout practices should be adhered to when designing
with the ADA4412-3. A solid ground plane is recommended,
and surface-mount, ceramic power supply decoupling
capacitors should be placed as close as possible to the supply
pins. All of the ADA4412-3 GND pins should be connected to
the ground plane with traces that are as short as possible.
Controlled impedance traces of the shortest length possible
should be used to connect to the signal I/O pins and should not
pass over any voids in the ground plane. A 75 impedance
level is typically used in video applications. All signal outputs of
the ADA4412-3 should include series termination resistors
when driving transmission lines.
When the ADA4412-3 receives its inputs from a device
with current outputs, the required load resistor value for
the output current is often different from the characteristic
impedance of the signal traces. In this case, if the interconnec-
tions are sufficiently short (<< 0.1 wavelength), the trace does
not have to be terminated in its characteristic impedance.
Traces of 75 can be used in this instance, provided their
lengths are an inch or two at the most. This is easily achieved
because the ADA4412-3 and the device feeding it are usually
adjacent to each other, and connections can be made that are
less than one inch in length.
VIDEO ENCODER RECONSTRUCTION FILTER
The ADA4412-3 is easily applied as a reconstruction filter at the
DAC outputs of a video encoder. Figure 20 illustrates how to use
the ADA4412-3 in this type of application with an ADV7322 video
encoder in a single-supply application with ac-coupled outputs.
ADA4412-3
Rev. 0 | Page 12 of 16
Y/G
3
Pb/B
5
Pr/R
7
5V
(ANALOG)
LEVEL1
LEVEL2
VCC
13
1
20
DISABLE
2
F_SEL_A
8
F_SEL_B
9
CUTOFF
FREQUENCY
SELECT
INPUT
GND
4, 6, 10
VEE
15, 17
18
Y/G_OUT
16
Pb/B_OUT
14
Pr/R_OUT
0.1
F
19
VCC
ADA4412-3
DGND
11
ADV7322
VIDEO ENCODER
VIDEO
DAC
OUTPUTS
R
L
R
L
R
L
0.1
F
0.1
F
0.1
F
10k
DNP
0
634
75
220
F
75
220
F
75
220
F
05528-
024
Figure 20. The ADA4412-3 Applied as a Single-Supply Reconstruction Filter Following the ADV7322
ADA4412-3
Rev. 0 | Page 13 of 16
OUTLINE DIMENSIONS
20
11
10
1
PIN 1
8°
0°
0.236
BSC
0.154
BSC
0.010
0.004
0.012
0.008
0.025
BSC
COPLANARITY
0.004
0.065
0.049
0.069
0.053
SEATING
PLANE
0.010
0.006
0.050
0.016
0.341
BSC
COMPLIANT TO JEDEC STANDARDS MO-137-AD
Figure 21. 20-Lead Shrink Small Outline Package [QSOP]
(RQ-20)
Dimensions shown in inches
ORDERING GUIDE
Model
Temperature Range
Package Description
Order Quantity
Package Option
ADA4412-3ARQZ
1
40°C to +85°C
20-Lead QSOP
1
RQ-20
ADA4412-3ARQZ-R7
1
40°C to +85°C
20-Lead QSOP
1,000
RQ-20
ADA4412-3ARQZ-RL
1
40°C to +85°C
20-Lead QSOP
2,500
RQ-20
1
Z = Pb-free part.
ADA4412-3
Rev. 0 | Page 14 of 16
NOTES
ADA4412-3
Rev. 0 | Page 15 of 16
NOTES
ADA4412-3
Rev. 0 | Page 16 of 16
NOTES
© 2005 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D0552807/05(0)
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