High Speed, Low Cost,
Triple Op Amp
ADA4861-3
Rev. A
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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
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Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 ©2006 Analog Devices, Inc. All rights reserved.
FEATURES
High speed
730 MHz, −3 dB bandwidth
625 V/μs slew rate
13 ns settling time to 0.5%
Wide supply range: 5 V to 12 V
Low power: 6 mA/amplifier
0.1 dB flatness: 100 MHz
Differential gain: 0.01%
Differential phase: 0.02°
Low voltage offset: 100 μV (typical)
High output current: 25 mA
Power down
APPLICATIONS
Consumer video
Professional video
Broadband video
ADC buffers
Active filters
PIN CONFIGURATION
POWER DOWN 1
1
OUT 2
14
POWER DOWN 2
2
–IN 2
13
POWER DOWN 3
3
+IN 2
12
+V
S4
–V
S
11
+IN 1
5
+IN 3
10
–IN 1
6
–IN 3
9
OUT 1
7
OUT 3
8
ADA4861-3
05708-001
Figure 1.
GENERAL DESCRIPTION
The ADA4861-3 is a low cost, high speed, current feedback,
triple op amp that provides excellent overall performance. The
730 MHz, −3 dB bandwidth, and 625 V/μs slew rate make this
amplifier well suited for many high speed applications. With its
combination of low price, excellent differential gain (0.01%),
differential phase (0.02°), and 0.1 dB flatness out to 100 MHz,
this amplifier is ideal for both consumer and professional video
applications.
The ADA4861-3 is designed to operate on supply voltages as
low as +5 V and up to ±5 V using only 6 mA/amplifier of supply
current. To further reduce power consumption, each amplifier
is equipped with a power-down feature that lowers the supply
current to 0.3 mA/amplifier when not being used.
The ADA4861-3 is available in a 14-lead SOIC_N package and
is designed to work over the extended temperature range of
−40°C to +105°C.
6.1
6.0
5.9
5.8
5.7
5.6
5.5
5.4
5.3
5.2
5.1
0.1 1 10 100 1000
05708-011
CLOSED-LOOP GAIN (dB)
FREQUENCY (MHz)
G = +2
V
OUT
= 2V p-p
R
F
= R
G
= 301Ω
V
S
= +5V
V
S
= ±5V
Figure 2. Large Signal 0.1 dB Flatness
ADA4861-3
Rev. A | Page 2 of 16
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Pin Configuration............................................................................. 1
General Description......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 5
Thermal Resistance ...................................................................... 5
ESD Caution.................................................................................. 5
Typical Performance Characteristics ............................................. 6
Applications..................................................................................... 13
Gain Configurations .................................................................. 13
20 MHz Active Low-Pass Filter................................................ 13
RGB Video Driver ...................................................................... 14
Driving Two Video Loads ......................................................... 14
POWER-DOWN Pins ............................................................... 14
Single-Supply Operation ........................................................... 15
Power Supply Bypassing............................................................ 15
Layout .......................................................................................... 15
Outline Dimensions ....................................................................... 16
Ordering Guide .......................................................................... 16
REVISION HISTORY
3/06—Rev 0 to Rev. A
Changes to 20 MHz Active Low-Pass Filter Section.................. 13
Changes to Figure 48 and Figure 49............................................. 13
10/05—Revision 0: Initial Version
ADA4861-3
Rev. A | Page 3 of 16
SPECIFICATIONS
VS = +5 V (@ TA = 25°C, G = +2, RL = 150 Ω, CL = 4 pF, unless otherwise noted); for G = +2, RF = RG = 301 Ω; and for G = +1, RF = 499 Ω.
Table 1.
Parameter Conditions Min Typ Max Unit
DYNAMIC PERFORMANCE
–3 dB Bandwidth VO = 0.2 V p-p 350 MHz
V
O = 2 V p-p 145 MHz
G = +1, VO = 0.2 V p-p 560 MHz
Bandwidth for 0.1 dB Flatness VO = 2 V p-p 85 MHz
+Slew Rate (Rising Edge) VO = 2 V p-p 590 V/μs
−Slew Rate (Falling Edge) VO = 2 V p-p 480 V/μs
Settling Time to 0.5% (Rise/Fall) VO = 2 V step 12/13 ns
NOISE/DISTORTION PERFORMANCE
Harmonic Distortion HD2/HD3 fC = 1 MHz, VO = 2 V p-p −81/−89 dBc
Harmonic Distortion HD2/HD3 fC = 5 MHz, VO = 2 V p-p −69/−76 dBc
Input Voltage Noise f = 100 kHz 3.8 nV/√Hz
Input Current Noise f = 100 kHz, +IN/−IN 1.7/5.5 pA/√Hz
Differential Gain 0.02 %
Differential Phase 0.03 Degrees
All-Hostile Crosstalk Amplifier 1 and Amplifier 2 driven,
Amplifier 3 output measured, f = 1 MHz
−65 dB
DC PERFORMANCE
Input Offset Voltage −13 −0.9 +13 mV
+Input Bias Current −2 −0.8 +1 μA
−Input Bias Current −8 +2.3 +13 μA
Open-Loop Transresistance 400 620 kΩ
INPUT CHARACTERISTICS
Input Resistance +IN 14 MΩ
−IN 85 Ω
Input Capacitance +IN 1.5 pF
Input Common-Mode Voltage Range G = +1 1.2 to 3.8 V
Common-Mode Rejection Ratio VCM = 2 V to 3 V −54 −56.5 dB
POWER-DOWN PINS
Input Voltage Enabled 0.6 V
Power down 1.8 V
Bias Current Enabled −3 μA
Power down 115 μA
Turn-On Time 200 ns
Turn-Off Time 3.5 μs
OUTPUT CHARACTERISTICS
Output Overdrive Recovery Time (Rise/Fall) VIN = +2.25 V to −0.25 V 55/100 ns
Output Voltage Swing RL = 150 Ω 1.2 to 3.8 1.1 to 3.9 V
R
L = 1 kΩ 0.9 to 4.1 0.85 to 4.15 V
Short-Circuit Current Sinking and sourcing 65 mA
POWER SUPPLY
Operating Range 5 12 V
Total Quiescent Current Enabled 12.5 16.1 18.5 mA
Quiescent Current/Amplifier POWER DOWN pins = +VS 0.2 0.33 mA
Power Supply Rejection Ratio
+PSR +VS = 4 V to 6 V, −VS = 0 V −60 −64 dB
ADA4861-3
Rev. A | Page 4 of 16
VS = ±5 V (@ TA = 25°C, G = +2, RL = 150 Ω, CL = 4 pF, unless otherwise noted); for G = +2, RF = RG = 301 Ω; and for G = +1, RF = 499 Ω.
Table 2.
Parameter Conditions Min Typ Max Unit
DYNAMIC PERFORMANCE
–3 dB Bandwidth VO = 0.2 V p-p 370 MHz
V
O = 2 V p-p 210 MHz
G = +1, VO = 0.2 V p-p 730 MHz
Bandwidth for 0.1 dB Flatness VO = 2 V p-p 100 MHz
+Slew Rate (Rising Edge) VO = 2 V p-p 910 V/μs
−Slew Rate (Falling Edge) VO = 2 V p-p 680 V/μs
Settling Time to 0.5% (Rise/Fall) VO = 2 V step 12/13 ns
NOISE/DISTORTION PERFORMANCE
Harmonic Distortion HD2/HD3 fC = 1 MHz, VO = 2 V p-p −85/−99 dBc
Harmonic Distortion HD2/HD3 fC = 5 MHz, VO = 2 V p-p −73/−86 dBc
Input Voltage Noise f = 100 kHz 3.8 nV/√Hz
Input Current Noise f = 100 kHz, +IN/−IN 1.7/5.5 pA/√Hz
Differential Gain 0.01 %
Differential Phase 0.02 Degrees
All-Hostile Crosstalk Amplifier 1 and Amplifier 2 driven,
Amplifier 3 output measured, f = 1 MHz
−65 dB
DC PERFORMANCE
Input Offset Voltage −13 −0.1 +13 mV
+Input Bias Current −2 −0.7 +1 μA
−Input Bias Current −8 +2.9 +13 μA
Open-Loop Transresistance 500 720 kΩ
INPUT CHARACTERISTICS
Input Resistance +IN 15 MΩ
−IN 90 Ω
Input Capacitance +IN 1.5 pF
Input Common-Mode Voltage Range G = +1 −3.7 to +3.7 V
Common-Mode Rejection Ratio VCM = ±2 V −55 −58 dB
POWER-DOWN PINS
Input Voltage Enabled −4.4 V
Power down −3.2 V
Bias Current Enabled −3 μA
Power down 250 μA
Turn-On Time 200 ns
Turn-Off Time 3.5 μs
OUTPUT CHARACTERISTICS
Output Overdrive Recovery Time (Rise/Fall) VIN = ±3.0 V 30/90 ns
Output Voltage Swing RL = 150 Ω ±2 −3.1 to +3.65 V
R
L = 1 kΩ ±3.9 ±4.05 V
Short-Circuit Current Sinking and sourcing 100 mA
POWER SUPPLY
Operating Range 5 12 V
Total Quiescent Current Enabled 13.5 17.9 20.5 mA
Quiescent Current/Amplifier POWER DOWN pins = +VS 0.3 0.5 mA
Power Supply Rejection Ratio
+PSR +VS = 4 V to 6 V, −VS = −5 V −63 −66 dB
−PSR +VS = 5 V, −VS = −4 V to −6 V,
POWER DOWN pins = −VS
−59 −62 dB
ADA4861-3
Rev. A | Page 5 of 16
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Rating
The power dissipated in the package (PD) is the sum of the
quiescent power dissipation and the power dissipated in the die
due to the amplifiers’ drive at the output. The quiescent power
is the voltage between the supply pins (VS) times the quiescent
current (IS).
Supply Voltage 12.6 V
Power Dissipation See Figure 3
Common-Mode Input Voltage −VS + 1 V to +VS − 1 V
Differential Input Voltage ±VS PD = Quiescent Power + (Total Drive Power − Load Power)
Storage Temperature −65°C to +125°C
()
L
OUT
L
OUT
S
SS
DR
V
R
VV
IVP
2
–
2⎟
⎠
⎞
⎜
⎝
⎛×+×=
Operating Temperature Range −40°C to +105°C
Lead Temperature JEDEC J-STD-20
Junction Temperature 150°C
RMS output voltages should be considered.
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.
Airflow increases heat dissipation, effectively reducing θJA.
In addition, more metal directly in contact with the package
leads and through holes under the device reduces θJA.
Figure 3 shows the maximum safe power dissipation in the
package vs. the ambient temperature for the 14-lead SOIC_N
(90°C/W) on a JEDEC standard 4-layer board. θJA values are
approximations.
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, θJA is
specified for device soldered in circuit board for surface-mount
packages.
2.5
0
AMBIENT TEMPERATURE (°C)
MAXIMUM POWER DISSIPATION (W)
05708-002
–55 125–45–35–25–15–5 5 152535455565758595105115
2.0
1.5
1.0
0.5
Table 4. Thermal Resistance
Package Type θJA Unit
14-lead SOIC_N 90 °C/W
Maximum Power Dissipation
The maximum safe power dissipation for the ADA4861-3 is
limited by the associated rise in junction temperature (TJ) on
the die. At approximately 150°C, which is the glass transition
temperature, the plastic changes its properties. Even temporarily
exceeding this temperature limit can change the stresses that the
package exerts on the die, permanently shifting the parametric
performance of the amplifiers. Exceeding a junction temperature of
150°C for an extended period can result in changes in silicon
devices, potentially causing degradation or loss of functionality.
Figure 3. 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.
ADA4861-3
Rev. A | Page 6 of 16
TYPICAL PERFORMANCE CHARACTERISTICS
RL = 150 Ω and CL = 4 pF, unless otherwise noted.
1
–6
–5
–4
–3
–2
–1
0
0.1 1 10 100 1000
05708-038
NORMALIZED GAIN (dB)
FREQUENCY (MHz)
G = +1,
R
F
= 499Ω
G = +2, R
F
= R
G
= 301Ω
G = –1, R
F
= R
G
= 301Ω
G = +5, R
F
= 200Ω, R
G
= 49.9Ω
G = +10, R
F
= 200Ω, R
G
= 22.1Ω
V
S
= ±5V
V
OUT
= 0.2V p-p
1
–6
–5
–4
–3
–2
–1
0
0.1 1 10 100 1000
05708-037
NORMALIZED GAIN (dB)
FREQUENCY (MHz)
V
S
= 5V
V
OUT
= 0.2V p-p
G = +1, R
F
= 499Ω
G = +2, R
F
= R
G
= 301Ω
G = –1, R
F
= R
G
= 301Ω
G = +5, R
F
= 200Ω, R
G
= 49.9Ω
G = +10, R
F
= 200Ω, R
G
= 22.1Ω
Figure 4. Small Signal Frequency Response for Various Gains
Figure 7. Small Signal Frequency Response for Various Gains
1
–6
–5
–4
–3
–2
–1
0
0.1 1 10 100 1000
05708-028
NORMALIZED GAIN (dB)
FREQUENCY (MHz)
G = –1, R
F
= R
G
= 301Ω
G = +5, R
F
= 200Ω, R
G
= 49.9Ω
G = +2, R
F
= R
G
= 301Ω
G = +1, R
F
= 499Ω
G = +10, R
F
= 200Ω, R
G
= 22.1Ω
V
S
= ±5V
V
OUT
= 2V p-p
1
–6
–5
–4
–3
–2
–1
0
0.1 1 10 100 1000
05708-027
NORMALIZED GAIN (dB)
FREQUENCY (MHz)
G = –1, R
F
= R
G
= 301Ω
G = +5, R
F
= 200Ω, R
G
= 49.9Ω
G = +2, R
F
= R
G
= 301Ω
G = +1, R
F
= 499Ω
G = +10, R
F
= 200Ω, R
G
= 22.1Ω
V
S
= 5V
V
OUT
= 2V p-p
Figure 8. Large Signal Frequency Response for Various Gains
Figure 5. Large Signal Frequency Response for Various Gains
7
0
1
2
3
4
5
6
0.1 1 10 100 1000
05708-029
CLOSED-LOOP GAIN (dB)
FREQUENCY (MHz)
V
S
= ±5V
G = +2 V
OUT
= 1V p-p
V
OUT
= 2V p-p
V
OUT
= 4V p-p
6.1
6.0
5.9
5.8
5.7
5.6
5.5
5.4
5.3
5.2
5.1
0.1 1 10 100 1000
05708-011
CLOSED-LOOP GAIN (dB)
FREQUENCY (MHz)
G = +2
V
OUT
= 2V p-p
R
F
= R
G
= 301Ω
V
S
= +5V
V
S
= ±5V
Figure 6. Large Signal 0.1 dB Flatness
Figure 9. Large Signal Frequency Response for Various Output Levels
ADA4861-3
Rev. A | Page 7 of 16
7
6
5
4
3
2
1
0
0.1 1 10 100 1000
05708-012
CLOSED-LOOP GAIN (dB)
FREQUENCY (MHz)
V
S
= ±5V
G = +2
R
G
= R
F
V
OUT
= 0.2V p-p
R
F
= 499Ω
R
F
= 301Ω
R
F
= 402Ω
R
F
= 604Ω
7
6
5
4
3
2
1
0
0.1 1 10 100 1000
05708-013
CLOSED-LOOP GAIN (dB)
FREQUENCY (MHz)
V
S
= ±5V
G = +2
R
F
= R
G
V
OUT
= 2V p-p
R
F
= 499Ω
R
F
= 301Ω
R
F
= 402Ω
R
F
= 604Ω
Figure 13. Large Signal Frequency Response vs. RF
Figure 10. Small Signal Frequency Response vs. RF
DISTORTION (dBc)
05708-049
–
40
15
–
0
FREQUENCY (MHz)
10
–50
–60
–70
–80
–90
–100
V
S
= ±5V
G = +1
V
OUT
= 2V p-p
HD3
V
OUT
= 3V p-p
HD3
V
OUT
= 3V p-p
HD2
V
OUT
= 2V p-p
HD2
Figure 11. Harmonic Distortion vs. Frequency
DISTORTION (dBc)
05708-048
–
40
–110
15
0
FREQUENCY (MHz)
10
–50
–60
–70
–80
–90
–100
V
OUT
=2Vp-p
HD3
V
S
=5V
G=+1
V
OUT
=2Vp-p
HD2
V
OUT
=1Vp-p
HD3
V
OUT
=1Vp-p
HD2
Figure 12. Harmonic Distortion vs. Frequency
DISTORTION (dBc)
05708-051
40
150
FREQUENCY (MHz)
10
–50
–60
–70
–80
–90
–100
V
S
=±5V
G=+2
V
OUT
=3Vp-p
HD3
V
OUT
=2Vp-p
HD3
V
OUT
=3Vp-p
HD2
V
OUT
=2Vp-p
HD2
Figure 14. Harmonic Distortion vs. Frequency
–
DISTORTION (dBc)
05708-050
40
–110
150
FREQUENCY (MHz)
10
–50
–60
–70
–80
–90
–100
V
S
=5V
G=+2
V
OUT
=2Vp-p
HD3
V
OUT
=1Vp-p
HD2
V
OUT
=1Vp-p
HD3
V
OUT
=2Vp-p
HD2
Figure 15. Harmonic Distortion vs. Frequency
ADA4861-3
Rev. A | Page 8 of 16
OUTPUT VOLTAGE (V)
+V
S
= 5V, –V
S
= 0V
200
100
0
–100
–200
2.7
2.6
2.5
2.4
2.3
OUTPUT VOLTAGE (mV)
±V
S
= 5V
G = +1
V
OUT
= 0.2V p-p
TIME = 5ns/DIV
05708-015
V
S
= +5V
V
S
= ±5V
OUTPUT VOLTAGE (V)
+V
S
= 5V, –V
S
= 0V
200
100
0
–100
–200
2.7
2.6
2.5
2.4
2.3
OUTPUT VOLTAGE (mV)
±V
S
= 5V
G = +2
V
OUT
= 0.2V p-p
TIME = 5ns/DIV
V
S
= +5V
V
S
= ±5V
05708-014
Figure 16. Small Signal Transient Response for Various Supplies
Figure 19. Small Signal Transient Response for Various Supplies
200
100
0
–100
–200
OUTPUT VOLTAGE (mV)
05708-040
V
S
= ±5V
G = +1
V
OUT
= 0.2V p-p
TIME = 5ns/DIV
C
L
= 9pF
C
L
= 4pF
C
L
= 6pF
200
100
0
–100
–200
OUTPUT VOLTAGE (mV)
05708-042
V
S
= ±5V
G = +2
V
OUT
= 0.2V p-p
TIME = 5ns/DIV
C
L
= 9pF C
L
= 4pF
C
L
= 6pF
Figure 17. Small Signal Transient Response for Various Capacitor Loads
Figure 20. Small Signal Transient Response for Various Capacitor Loads
2.7
2.6
2.5
2.4
2.3
OUTPUT VOLTAGE (V)
05708-039
V
S
= 5V
G = +1
V
OUT
= 0.2V p-p
TIME = 5ns/DIV
C
L
= 9pF
C
L
= 4pF
C
L
= 6pF
2.7
2.6
2.5
2.4
2.3
OUTPUT VOLTAGE (V)
05708-041
V
S
= 5V
G = +2
V
OUT
= 0.2V p-p
TIME = 5ns/DIV
C
L
= 9pF C
L
= 4pF
C
L
= 6pF
Figure 21. Small Signal Transient Response for Various Capacitor Loads
Figure 18. Small Signal Transient Response for Various Capacitor Loads
ADA4861-3
Rev. A | Page 9 of 16
OUTPUT VOLTAGE (V)
+V
S
= 5V, –V
S
= 0V
1.5
0.5
0
–1.0
1.0
–0.5
–1.5
4.0
3.0
2.5
1.5
3.5
2.0
1.0
OUTPUT VOLTAGE (V)
±V
S
= 5V
G = +1
V
OUT
= 2V p-p
TIME = 5ns/DIV
V
S
= ±5V
05708-017
V
S
= +5V
OUTPUT VOLTAGE (V)
+V
S
= 5V, –V
S
= 0V
1.5
0.5
0
–1.0
1.0
–0.5
–1.5
4.0
3.0
2.5
1.5
3.5
2.0
1.0
OUTPUT VOLTAGE (V)
±V
S
= 5V
G = +2
V
OUT
= 2V p-p
TIME = 5ns/DIV
V
S
= ±5V
05708-016
V
S
= +5V
Figure 22. Large Signal Transient Response for Various Supplies
Figure 25. Large Signal Transient Response for Various Supplies
1.5
–1.5
–1.0
–0.5
0
0.5
1.0
OUTPUT VOLTAGE (V)
05708-031
V
S
= ±5V
G = +1
V
OUT
= 2V p-p
TIME = 5ns/DIV
C
L
= 9pF
C
L
= 4pF
C
L
= 6pF 1.5
–1.0
–0.5
0
0.5
1.0
OUTPUT VOLTAGE (V)
05708-033
V
S
= ±5V
G = +2
V
OUT
= 2V p-p
TIME = 5ns/DIV
C
L
= 9pF
C
L
= 4pF
C
L
= 6pF
–1.5
Figure 26. Large Signal Transient Response for Various Capacitor Loads
Figure 23. Large Signal Transient Response for Various Capacitor Loads
4.0
1.0
1.5
2.0
2.5
3.0
3.5
OUTPUT VOLTAGE (V)
05708-032
V
S
= 5V
G = +2
V
OUT
= 2V p-p
TIME = 5ns/DIV
C
L
= 9pF
C
L
= 4pF
C
L
= 6pF
4.0
1.0
1.5
2.0
2.5
3.0
3.5
OUTPUT VOLTAGE (V)
05708-030
V
S
= 5V
G = +1
V
OUT
= 2V p-p
TIME = 5ns/DIV
C
L
= 9pF
C
L
= 4pF
C
L
= 6pF
Figure 27. Large Signal Transient Response for Various Capacitor Loads
Figure 24. Large Signal Transient Response for Various Capacitor Loads
ADA4861-3
Rev. A | Page 10 of 16
4.54.03.53.02.52.01.51.00.5
05708-036
SLEW RATE (V/µs)
INPUT VOLTAGE (V p-p)
1800
1600
1400
1200
1000
800
600
400
200
005
.0
1400
0
200
400
600
800
1000
1200
02.252.001.751.501.251.000.750.500.25 2.50
05708-018
SLEW RATE (V/µs)
INPUT VOLTAGE (V p-p)
V
S
= ±5V
G = +1 V
S
= ±5V
G = +2
POSITIVE SLEW RATE
NEGATIVE SLEW RATE
POSITIVE SLEW RATE
NEGATIVE SLEW RATE
Figure 28. Slew Rate vs. Input Voltage
Figure 31. Slew Rate vs. Input Voltage
700
0
100
200
300
400
500
600
022.01.51.00.5 3.0
05708-021
SLEW RATE (V/µs)
INPUT VOLTAGE (V p-p)
V
S
= 5V
G = +1
.5
POSITIVE SLEW RATE
NEGATIVE SLEW RATE
700
0
100
200
300
400
500
600
011.000.750.500.25 1.50
05708-019
SLEW RATE (V/µs)
INPUT VOLTAGE (V p-p)
V
S
= 5V
G = +2
.25
POSITIVE SLEW RATE
NEGATIVE SLEW RATE
Figure 29. Slew Rate vs. Input Voltage
Figure 32. Slew Rate vs. Input Voltage
1.00
t = 0s
–1.00
–0.75
–0.50
–0.25
0
0.25
0.50
0.75
05708-022
SETTLING TIME (%)
V
S
= ±5V
G = +2
V
OUT
= 2V p-p
TIME = 5ns/DIV
V
IN
1V
1.00 t = 0s
1V
–1.00
–0.75
–0.50
–0.25
0
0.25
0.50
0.75
05708-020
SETTLING TIME (%)
V
S
= ±5V
G = +2
V
OUT
= 2V p-p
TIME = 5ns/DIV
V
IN
Figure 30. Settling Time Rising Edge
Figure 33. Settling Time Falling Edge
ADA4861-3
Rev. A | Page 11 of 16
0
–10
–20
–40
–30
–50
–60
–70
–80
–90
–100
0.1 1 10 100 1000
05708-024
CROSSTALK (dB)
FREQUENCY (MHz)
V
S
= ±5V, +5V
G = +2
V
OUT
= 2V p-p
1000
0.1
1
10
100
–180
–135
–90
–45
0
0.01 0.1 1 10 100 1000
05708-044
TRANSIMPEDANCE (kΩ)
PHASE (Degrees)
FREQUENCY (MHz)
V
S
= ±5V
G = +2
TRANSIMPEDANCE
PHASE
Figure 37. Large Signal All-Hostile Crosstalk
Figure 34. Transimpedance and Phase vs. Frequency
0
–70
–60
–50
–40
–30
–20
–10
0.01 0.1 1 10 100 1000
05708-045
COMMON-MODE REJECTION (dB)
FREQUENCY (MHz)
V
S
= ±5V
G = +2
V
IN
= 2V p-p
0
–80
–70
–60
–50
–40
–30
–20
–10
0.01 0.1 1 10 100 1000
05708-023
POWER SUPPLY REJECTION (dB)
FREQUENCY (MHz)
V
S
= ±5V
G = +2
–PSR
+PSR
Figure 38. Common-Mode Rejection vs. Frequency
Figure 35. Power Supply Rejection vs. Frequency
6
–6
–5
–4
–3
–2
–1
0
1
2
3
4
5
0 1000900800700600500400300200100
05708-035
OUTPUT AND INPUT VOLTAGE (V)
TIME (ns)
INPUT VOLTAGE × 2
OUTPUT VOLTAGE
V
S
= ±5V
G = +2
f = 1MHz
5.5
–0.5
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0 1000900800700600500400300200100
05708-034
OUTPUT AND INPUT VOLTAGE (V)
TIME (ns)
INPUT VOLTAGE × 2
OUTPUT VOLTAGE
V
S
= 5V
G = +2
f = 1MHz
Figure 36. Output Overdrive Recovery
Figure 39. Output Overdrive Recovery
ADA4861-3
Rev. A | Page 12 of 16
35
0
5
10
15
20
25
30
10 100 1k 10k 100k
05708-052
INPUT VOLTAGE NOISE (nV/ Hz)
FREQUENCY (Hz)
V
S
= ±5V, +5V 60
0
10
20
30
40
50
10 100 1k 10k 100k
05708-053
INPUT CURRENT NOISE (pA/ Hz)
FREQUENCY (Hz)
V
S
= ±5V, +5V
NONINVERTING
INPUT
INVERTING INPUT
Figure 40. Input Voltage Noise vs. Frequency
Figure 43. Input Current Noise vs. Frequency
19
18
17
16
15
TOTAL SUPPLY CURRENT (mA)
05708-043
14 4 5 6 7 8 9 10 11 12
SUPPLY VOLTAGE (V)
20
19
18
17
16
15
14
13
12
–40 1251109580655035205–10–25
05708-025
TOTAL SUPPLY CURRENT (mA)
TEMPERATURE (°C)
V
S
= ±5V
V
S
= +5V
Figure 41. Total Supply Current vs. Supply Voltage
Figure 44. Total Supply Current at Various Supplies vs. Temperature
25
–25
–20
–15
–10
–5
0
5
10
15
20
–5–4–3–2–1012345
05708-046
INPUT
V
OS
(mV)
V
CM
(V)
V
S
= ±5V V
S
= +5V
20
–15
–10
–5
0
5
10
15
–5–4–3–2–1012345
05708-026
INPUT BIAS CURRENT (μA)
OUTPUT VOLTAGE (V)
V
S
= ±5V
V
S
= +5V
Figure 42. Input VOS vs. Common-Mode Voltage
Figure 45. Input Bias Current vs. Output Voltage
ADA4861-3
Rev. A | Page 13 of 16
APPLICATIONS
GAIN CONFIGURATIONS 20 MHz ACTIVE LOW-PASS FILTER
Unlike conventional voltage feedback amplifiers, the feedback
resistor has a direct impact on the closed-loop bandwidth and
stability of the current feedback op amp circuit. Reducing the
resistance below the recommended value can make the amplifier
response peak and even become unstable. Increasing the size
of the feedback resistor reduces the closed-loop bandwidth.
The ADA4861-3 triple amplifier lends itself to higher order
active filters. Figure 48 shows a 28 MHz, 6-pole, Sallen-Key
low-pass filter.
V
IN
U1
OP AMP
OUT
+
–
R1
562Ω
R2
562Ω
C2
10pF
C1
10pF
R12
301Ω
R11
210kΩ
U2
OP AMP
OUT
+
–
R3
562Ω
R4
562Ω
C4
10pF
C3
10pF
R10
301Ω
R9
210Ω
05708-007
U3
OP AMP
OUT
+
–
R5
562Ω
R6
562Ω
C6
10pF
C5
10pF
R8
301Ω
R7
210Ω
V
OUT
Tabl e 5 provides a convenient reference for quickly determining
the feedback and gain set resistor values and bandwidth for
common gain configurations.
Table 5. Recommended Values and Frequency Performance1
Large Signal
0.1 dB Flatness
Gain RF (Ω) RG (Ω) −3 dB SS BW (MHz)
+1 499 N/A 730 90
−1 301 301 350 60
+2 301 301 370 100
+5 200 49.9 180 30
+10 200 22.1 80 15
1 Conditions: VS = ±5 V, TA = 25°C, RL = 150 Ω.
Figure 46 and Figure 47 show the typical noninverting and
inverting configurations and recommended bypass capacitor
values.
0
5708-005
0.1µF
10µF
–V
S
V
IN
R
G
V
OUT
10µF
0.1µF
+
V
S
ADA4861-3
+
–
R
F
Figure 48. 28 MHz, 6-Pole Low-Pass Filter
The filter has a gain of approximately 23 dB and flat frequency
response out to 22 MHz. This type of filter is commonly used at
the output of a video DAC as a reconstruction filter. The frequency
response of the filter is shown in Figure 49.
Figure 46. Noninverting Gain
30
20
–70
–60
–50
–40
–30
–20
–10
0
10
1 10 100 200
05708-047
MAGNITUDE (dB)
FREQUENCY (MHz)
0
5708-006
0.1µF
10µF
–VS
VIN
VOUT
10µF
0.1µF
+VS
ADA4861-3
+
–
RF
RG
Figure 47. Inverting Gain
Figure 49. 20 MHz Low-Pass Filter Frequency Response
ADA4861-3
Rev. A | Page 14 of 16
05708-004
75Ω
CABLE
75Ω
CABLE
75Ω
75Ω
75Ω
V
OUT
2
V
OUT
1
–V
S
+V
S
V
IN
0.1µF
0.1µF
10µF
10µF
75Ω
CABLE
75Ω
75Ω
+
–
R
F
301Ω
R
G
301Ω
ADA4861-3
RGB VIDEO DRIVER
Figure 50 shows a typical RGB driver application using bipolar
supplies. The gain of the amplifier is set at +2, where RF = RG =
301 Ω. The amplifier inputs are terminated with shunt 75 Ω
resistors, and the outputs have series 75 Ω resistors for proper
video matching. In Figure 50, the POWER-DOWN pins are not
shown connected to any signal source for simplicity. If the
power-down function is not used, it is recommended that the
power-down pins be tied to the negative supply and not be left
floating (not connected).
For applications that require a fixed gain of +2, consider using
the
Figure 51. Video Driver Schematic for Two Video Loads
ADA4862-3 with integrated RF and RG. The ADA4862-3 is
another high performance triple current feedback amplifier that
can simplify design and reduce board area.
0.1
–0.9
–0.8
–0.7
–0.6
–0.5
–0.4
–0.3
–0.2
–0.1
0
1 10 100 400
05708-010
NORMALIZED GAIN (dB)
FREQUENCY (MHz)
V
S
= ±5V
R
L
= 75Ω
V
OUT
= 2V p-p
RF
301Ω
RG
301Ω
75Ω
75Ω
VOUT (R)
VIN (R)
7
5
6
RF
301Ω
RG
301Ω
75Ω
75Ω
VOUT (G)
V
IN (G)
8
10
9
RF
301Ω
RG
301Ω
75Ω
75Ω
VOUT (B)
VIN (B)
14
12
13
123
10µF
0.1µF
+
V
S
4
0.1µF
10µF
–VS
11
PD1
PD2
PD3
05708-003
Figure 52. Large Signal Frequency Response for Various Supplies, RL = 75 Ω
POWER-DOWN PINS
The ADA4861-3 is equipped with three independent POWER
DOWN pins, one for each amplifier. This allows the user the
ability to reduce the quiescent supply current when an amplifier
is inactive. The power-down threshold levels are derived from
the voltage applied to the −VS pin. When used in single-supply
applications, this is especially useful with conventional logic
levels. The amplifier is powered down when the voltage applied
to the POWER DOWN pins is greater than −VS + 1 V. In a
single-supply application, this is > +1 V (that is, 0 V + 1 V), in a
±5 V supply application, the voltage is > −4 V. The amplifier is
enabled whenever the POWER DOWN pins are left either open
or the voltage on the POWER DOWN pins is lower than 1 V
above −VS. If the POWER DOWN pins are not used, it is best to
connect them to the negative supply.
Figure 50. RGB Video Driver
DRIVING TWO VIDEO LOADS
In applications that require two video loads be driven
simultaneously, the ADA4861-3 can deliver. Figure 51 shows
the ADA4861-3 configured with dual video loads. Figure 52
shows the dual video load 0.1 dB bandwidth performance.
ADA4861-3
Rev. A | Page 15 of 16
SINGLE-SUPPLY OPERATION POWER SUPPLY BYPASSING
The ADA4861-3 can also be operated from a single power
supply.
Careful attention must be paid to bypassing the power supply
pins of the ADA4861-3. High quality capacitors with low
equivalent series resistance (ESR), such as multilayer ceramic
capacitors (MLCCs), should be used to minimize supply voltage
ripple and power dissipation. A large, usually tantalum, 2.2 μF
to 47 μF capacitor located in proximity to the ADA4861-3 is
required to provide good decoupling for lower frequency
signals. The actual value is determined by the circuit transient
and frequency requirements. In addition, 0.1 μF MLCC
decoupling capacitors should be located as close to each of the
power supply pins as is physically possible, no more than 1/8
inch away. The ground returns should terminate immediately
into the ground plane. Locating the bypass capacitor return
close to the load return minimizes ground loops and improves
performance.
Figure 53 shows the schematic for a single 5 V supply
video driver. The input signal is ac-coupled into the amplifier
via C1. Resistor R2 and Resistor R4 establish the input midsupply
reference for the amplifier. Capacitor C5 prevents constant
current from being drawn through the gain set resistor and
enables the ADA4861-3 at dc to provide unity gain to the input
midsupply voltage, thereby establishing the output voltage dc
operating point. Capacitor C6 is the output coupling capacitor.
For more information on single-supply operation of op amps,
see www.analog.com/library/analogDialogue/archives/35-
02/avoiding/.
0
5708-054
C2
1µF
R2
50kΩ
R4
50kΩ
R3
1kΩ
C1
22µF
R1
50Ω
C6
220µF
R5
75ΩR6
75Ω
C5
22µF
ADA4861-3
+5V
V
OUT
V
IN
–V
S
C3
2.2µF
C4
0.01µF
+5
V
LAYOUT
As is the case with all high-speed applications, careful attention
to printed circuit board (PCB) layout details prevents associated
board parasitics from becoming problematic. The ADA4861-3
can operate at up to 730 MHz; therefore, proper RF design
techniques must be employed. The PCB should have a
ground plane covering all unused portions of the component
side of the board to provide a low impedance return path.
Removing the ground plane on all layers from the area near
and under the input and output pins reduces stray capacitance.
Signal lines connecting the feedback and gain resistors should
be kept as short as possible to minimize the inductance and
stray capacitance associated with these traces. Termination
resistors and loads should be located as close as possible to their
respective inputs and outputs. Input and output traces should
be kept as far apart as possible to minimize coupling (crosstalk)
through the board. Adherence to microstrip or stripline design
techniques for long signal traces (greater than 1 inch) is
recommended. For more information on high speed board
layout, go to:
Figure 53. Single-Supply Video Driver Schematic
www.analog.com and
www.analog.com/library/analogDialogue/archives/39-
09/layout.html.
ADA4861-3
Rev. A | Page 16 of 16
OUTLINE DIMENSIONS
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
COMPLIANT TO JEDEC STANDARDS MS-012-AB
COPLANARITY
0.10
14 8
7
1
6.20 (0.2441)
5.80 (0.2283)
4.00 (0.1575)
3.80 (0.1496)
8.75 (0.3445)
8.55 (0.3366)
1.27 (0.0500)
BSC
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0039)
0.51 (0.0201)
0.31 (0.0122)
1.75 (0.0689)
1.35 (0.0531)
8°
0°
0.50 (0.0197)
0.25 (0.0098)
1.27 (0.0500)
0.40 (0.0157)
0.25 (0.0098)
0.17 (0.0067)
× 45°
Figure 54. 14-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-14)
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model Temperature Range Package Description Package Option Ordering Quantity
ADA4861-3YRZ –40°C to +105°C 14-Lead SOIC_N R-14 1
1
ADA4861-3YRZ-RL –40°C to +105°C 14-Lead SOIC_N R-14 2,500
1
14-Lead SOIC_N ADA4861-3YRZ-RL7 –40°C to +105°C R-14 1,000
1
1 Z = Pb-free part.
©2006 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D05708-0-3/06(A)
