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High Speed, Low Cost, Triple Op Amp ADA4861-3
FEATURES
High speed 730 MHz, -3 dB bandwidth 625 V/s 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 V (typical) High output current: 25 mA Power down
PIN CONFIGURATION
POWER DOWN 1 1 POWER DOWN 2 2 POWER DOWN 3 3 +VS 4 +IN 1 5 -IN 1 6 OUT 1 7
14 OUT 2 13 -IN 2 12 +IN 2
ADA4861-3
11 -VS 10 +IN 3 9 8
-IN 3 OUT 3
05708-001
Figure 1.
APPLICATIONS
Consumer video Professional video Broadband video ADC buffers Active filters
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/s 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 -40C to +105C.
6.1 6.0 5.9
CLOSED-LOOP GAIN (dB)
G = +2 VOUT = 2V p-p RF = RG = 301
5.8 5.7 5.6 5.5 5.4 5.3 5.2 5.1 0.1 1 10 FREQUENCY (MHz) 100
05708-011
VS = 5V VS = +5V
1000
Figure 2. Large Signal 0.1 dB Flatness
Rev. A
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 (c)2006 Analog Devices, Inc. All rights reserved.
ADA4861-3 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
Rev. A | Page 2 of 16
ADA4861-3 SPECIFICATIONS
VS = +5 V (@ TA = 25C, G = +2, RL = 150 , CL = 4 pF, unless otherwise noted); for G = +2, RF = RG = 301 ; and for G = +1, RF = 499 . Table 1.
Parameter DYNAMIC PERFORMANCE -3 dB Bandwidth Conditions VO = 0.2 V p-p VO = 2 V p-p G = +1, VO = 0.2 V p-p VO = 2 V p-p VO = 2 V p-p VO = 2 V p-p VO = 2 V step fC = 1 MHz, VO = 2 V p-p fC = 5 MHz, VO = 2 V p-p f = 100 kHz f = 100 kHz, +IN/-IN Min Typ 350 145 560 85 590 480 12/13 -81/-89 -69/-76 3.8 1.7/5.5 0.02 0.03 -65 Max Unit MHz MHz MHz MHz V/s V/s ns dBc dBc nV/Hz pA/Hz % Degrees dB
Bandwidth for 0.1 dB Flatness +Slew Rate (Rising Edge) -Slew Rate (Falling Edge) Settling Time to 0.5% (Rise/Fall) NOISE/DISTORTION PERFORMANCE Harmonic Distortion HD2/HD3 Harmonic Distortion HD2/HD3 Input Voltage Noise Input Current Noise Differential Gain Differential Phase All-Hostile Crosstalk DC PERFORMANCE Input Offset Voltage +Input Bias Current -Input Bias Current Open-Loop Transresistance INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Common-Mode Rejection Ratio POWER-DOWN PINS Input Voltage Bias Current Turn-On Time Turn-Off Time OUTPUT CHARACTERISTICS Output Overdrive Recovery Time (Rise/Fall) Output Voltage Swing Short-Circuit Current POWER SUPPLY Operating Range Total Quiescent Current Quiescent Current/Amplifier Power Supply Rejection Ratio +PSR
Amplifier 1 and Amplifier 2 driven, Amplifier 3 output measured, f = 1 MHz -13 -2 -8 400 +IN -IN +IN G = +1 VCM = 2 V to 3 V Enabled Power down Enabled Power down
-0.9 -0.8 +2.3 620 14 85 1.5 1.2 to 3.8 -56.5 0.6 1.8 -3 115 200 3.5 55/100 1.1 to 3.9 0.85 to 4.15 65
+13 +1 +13
mV A A k M pF V dB V V A A ns s ns V V mA
-54
VIN = +2.25 V to -0.25 V RL = 150 RL = 1 k Sinking and sourcing
1.2 to 3.8 0.9 to 4.1
Enabled POWER DOWN pins = +VS +VS = 4 V to 6 V, -VS = 0 V
5 12.5
16.1 0.2 -64
12 18.5 0.33
V mA mA dB
-60
Rev. A | Page 3 of 16
ADA4861-3
VS = 5 V (@ TA = 25C, G = +2, RL = 150 , CL = 4 pF, unless otherwise noted); for G = +2, RF = RG = 301 ; and for G = +1, RF = 499 . Table 2.
Parameter DYNAMIC PERFORMANCE -3 dB Bandwidth Conditions VO = 0.2 V p-p VO = 2 V p-p G = +1, VO = 0.2 V p-p VO = 2 V p-p VO = 2 V p-p VO = 2 V p-p VO = 2 V step fC = 1 MHz, VO = 2 V p-p fC = 5 MHz, VO = 2 V p-p f = 100 kHz f = 100 kHz, +IN/-IN Min Typ 370 210 730 100 910 680 12/13 -85/-99 -73/-86 3.8 1.7/5.5 0.01 0.02 -65 Max Unit MHz MHz MHz MHz V/s V/s ns dBc dBc nV/Hz pA/Hz % Degrees dB
Bandwidth for 0.1 dB Flatness +Slew Rate (Rising Edge) -Slew Rate (Falling Edge) Settling Time to 0.5% (Rise/Fall) NOISE/DISTORTION PERFORMANCE Harmonic Distortion HD2/HD3 Harmonic Distortion HD2/HD3 Input Voltage Noise Input Current Noise Differential Gain Differential Phase All-Hostile Crosstalk DC PERFORMANCE Input Offset Voltage +Input Bias Current -Input Bias Current Open-Loop Transresistance INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Common-Mode Rejection Ratio POWER-DOWN PINS Input Voltage Bias Current Turn-On Time Turn-Off Time OUTPUT CHARACTERISTICS Output Overdrive Recovery Time (Rise/Fall) Output Voltage Swing Short-Circuit Current POWER SUPPLY Operating Range Total Quiescent Current Quiescent Current/Amplifier Power Supply Rejection Ratio +PSR -PSR
Amplifier 1 and Amplifier 2 driven, Amplifier 3 output measured, f = 1 MHz -13 -2 -8 500 +IN -IN +IN G = +1 VCM = 2 V Enabled Power down Enabled Power down
-0.1 -0.7 +2.9 720 15 90 1.5 -3.7 to +3.7 -58 -4.4 -3.2 -3 250 200 3.5 30/90 -3.1 to +3.65 4.05 100
+13 +1 +13
mV A A k M pF V dB V V A A ns s ns V V mA
-55
VIN = 3.0 V RL = 150 RL = 1 k Sinking and sourcing
2 3.9
Enabled POWER DOWN pins = +VS +VS = 4 V to 6 V, -VS = -5 V +VS = 5 V, -VS = -4 V to -6 V, POWER DOWN pins = -VS
5 13.5
17.9 0.3 -66 -62
12 20.5 0.5
V mA mA dB dB
-63 -59
Rev. A | Page 4 of 16
ADA4861-3 ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Supply Voltage Power Dissipation Common-Mode Input Voltage Differential Input Voltage Storage Temperature Operating Temperature Range Lead Temperature Junction Temperature Rating 12.6 V See Figure 3 -VS + 1 V to +VS - 1 V VS -65C to +125C -40C to +105C JEDEC J-STD-20 150C
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). PD = Quiescent Power + (Total Drive Power - Load Power)
V V V 2 PD = (VS x I S ) + S x OUT - OUT RL RL 2
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.
RMS output voltages should be considered. Airflow increases heat dissipation, effectively reducing JA. In addition, more metal directly in contact with the package leads and through holes under the device reduces JA. Figure 3 shows the maximum safe power dissipation in the package vs. the ambient temperature for the 14-lead SOIC_N (90C/W) on a JEDEC standard 4-layer board. JA values are approximations.
2.5
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 14-lead SOIC_N JA 90 Unit C/W
MAXIMUM POWER DISSIPATION (W)
2.0
1.5
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 150C, 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 150C for an extended period can result in changes in silicon devices, potentially causing degradation or loss of functionality.
1.0
0.5
05708-002
0
-55 -45 -35 -25 -15 -5 5 15 25 35 45 55 65 75 85 95 105 115 125
AMBIENT TEMPERATURE (C)
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.
Rev. A | Page 5 of 16
ADA4861-3 TYPICAL PERFORMANCE CHARACTERISTICS
RL = 150 and CL = 4 pF, unless otherwise noted.
1 0
NORMALIZED GAIN (dB)
VS = 5V VOUT = 0.2V p-p
G = +1, RF = 499
1 0
NORMALIZED GAIN (dB)
VS = 5V VOUT = 0.2V p-p
G = +1, RF = 499
-1 -2 -3 -4
G = +2, RF = RG = 301 G = -1, RF = RG = 301
-1 -2
G = +2, RF = RG = 301 G = -1, RF = RG = 301
G = +5, RF = 200, RG = 49.9
-3 G = +5, RF = 200, RG = 49.9 -4 G = +10, RF = 200, RG = 22.1 -5 -6 0.1
G = +10, RF = 200, RG = 22.1
05708-038
-6 0.1
1
10 FREQUENCY (MHz)
100
1000
1
10 FREQUENCY (MHz)
100
1000
Figure 4. Small Signal Frequency Response for Various Gains
1 0
NORMALIZED GAIN (dB)
Figure 7. Small Signal Frequency Response for Various Gains
1
VS = 5V VOUT = 2V p-p
G = -1, RF = RG = 301 0
NORMALIZED GAIN (dB)
VS = 5V VOUT = 2V p-p
G = +5, RF = 200, RG = 49.9
-1 -2 -3 -4 -5 -6 0.1
G = +5, RF = 200, RG = 49.9 G = +1, RF = 499 G = +2, RF = RG = 301
-1 -2
G = +1, RF = 499
G = +2, RF = RG = 301 -3 -4 -5 -6 0.1 G = +10, RF = 200, RG = 22.1
05708-028
G = +10, RF = 200, RG = 22.1
1
10 FREQUENCY (MHz)
100
1000
1
10 FREQUENCY (MHz)
100
1000
Figure 5. Large Signal Frequency Response for Various Gains
6.1 6.0 5.9
CLOSED-LOOP GAIN (dB) CLOSED-LOOP GAIN (dB)
Figure 8. Large Signal Frequency Response for Various Gains
7 6 5 VOUT = 2V p-p 4 3 VOUT = 4V p-p 2 1 0 0.1
G = +2 VOUT = 2V p-p RF = RG = 301
VS = 5V G = +2
VOUT = 1V p-p
5.8 5.7 5.6 5.5 5.4 5.3 5.2 5.1 0.1 1 10 FREQUENCY (MHz) 100
05708-011
VS = 5V VS = +5V
1000
1
10 FREQUENCY (MHz)
100
1000
Figure 6. Large Signal 0.1 dB Flatness
Figure 9. Large Signal Frequency Response for Various Output Levels
Rev. A | Page 6 of 16
05708-029
05708-027
G = -1, RF = RG = 301
05708-037
-5
ADA4861-3
7 6
CLOSED-LOOP GAIN (dB)
7
RF = 301 RF = 402
6
RF = 301 RF = 402
5 RF = 499 4 3 2 1 VS = 5V G = +2 RG = RF VOUT = 0.2V p-p 1 10 FREQUENCY (MHz) 100 RF = 604
CLOSED-LOOP GAIN (dB)
5 RF = 499 4 3 2 1 0 0.1 VS = 5V G = +2 RF = RG VOUT = 2V p-p 1 10 FREQUENCY (MHz) 100 RF = 604
0 0.1
1000
1000
Figure 10. Small Signal Frequency Response vs. RF
-40 -40 VS = 5V G = +1 -50
Figure 13. Large Signal Frequency Response vs. RF
VS = 5V G = +2
-50
DISTORTION (dBc)
-60 VOUT = 2V p-p HD2
VOUT = 3V p-p HD2
DISTORTION (dBc)
-60
VOUT = 3V p-p HD2 VOUT = 2V p-p HD2
-70
-70
-80
VOUT = 2V p-p HD3 VOUT = 3V p-p HD3 1 10 FREQUENCY (MHz)
-80
VOUT = 3V p-p HD3 VOUT = 2V p-p HD3
-90
-90
05708-049
-100
-100
50
1
10 FREQUENCY (MHz)
50
Figure 11. Harmonic Distortion vs. Frequency
-40 -50 -60 VOUT = 2V p-p HD2 -40 VOUT = 2V p-p HD3
Figure 14. Harmonic Distortion vs. Frequency
VS = 5V G = +1
VS = 5V G = +2 -50 -60 VOUT = 2V p-p HD3 VOUT = 2V p-p HD2
DISTORTION (dBc)
-70 -80 -90 -100 -110 VOUT = 1V p-p HD2 VOUT = 1V p-p HD3
05708-048
DISTORTION (dBc)
-70 -80 -90 -100 -110 VOUT = 1V p-p HD3
05708-050
VOUT = 1V p-p HD2
1
10 FREQUENCY (MHz)
50
1
10 FREQUENCY (MHz)
50
Figure 12. Harmonic Distortion vs. Frequency
Figure 15. Harmonic Distortion vs. Frequency
Rev. A | Page 7 of 16
05708-051
05708-013
05708-012
ADA4861-3
200 VS = +5V 2.7 200 VS = +5V 2.7
OUTPUT VOLTAGE (mV) VS = 5V
OUTPUT VOLTAGE (mV) VS = 5V
OUTPUT VOLTAGE (V) +VS = 5V, -VS = 0V
VS = 5V 0 2.5
VS = 5V 0 2.5
-100 G = +1 VOUT = 0.2V p-p TIME = 5ns/DIV
2.4
05708-015
-100 G = +2 VOUT = 0.2V p-p TIME = 5ns/DIV
2.4
05708-014
-200
2.3
-200
2.3
Figure 16. Small Signal Transient Response for Various Supplies
200
Figure 19. Small Signal Transient Response for Various Supplies
200
CL = 9pF CL = 6pF
CL = 9pF 100
CL = 4pF
OUTPUT VOLTAGE (mV)
CL = 4pF 0
OUTPUT VOLTAGE (mV)
100
CL = 6pF 0
-100
05708-040
-200
-200
Figure 17. Small Signal Transient Response for Various Capacitor Loads
2.7
Figure 20. Small Signal Transient Response for Various Capacitor Loads
2.7
CL = 9pF CL = 6pF
CL = 9pF 2.6
CL = 4pF
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
2.6 CL = 4pF 2.5
CL = 6pF 2.5
2.4
2.4
05708-039
2.3
2.3
Figure 18. Small Signal Transient Response for Various Capacitor Loads
Figure 21. Small Signal Transient Response for Various Capacitor Loads
Rev. A | Page 8 of 16
05708-041
VS = 5V G = +1 VOUT = 0.2V p-p TIME = 5ns/DIV
VS = 5V G = +2 VOUT = 0.2V p-p TIME = 5ns/DIV
05708-042
VS = 5V G = +1 VOUT = 0.2V p-p TIME = 5ns/DIV
-100
VS = 5V G = +2 VOUT = 0.2V p-p TIME = 5ns/DIV
OUTPUT VOLTAGE (V) +VS = 5V, -VS = 0V
100
2.6
100
2.6
ADA4861-3
1.5 VS = +5V 4.0 1.5 VS = +5V 4.0
1.0
3.5
1.0
3.5 VS = 5V
OUTPUT VOLTAGE (V) VS = 5V
OUTPUT VOLTAGE (V) +VS = 5V, -VS = 0V
OUTPUT VOLTAGE (V) VS = 5V
0.5
3.0
0.5
3.0
0
2.5
0
2.5
-0.5
2.0
-0.5
2.0
-1.0
05708-017
-1.5
1.0
-1.5
1.0
Figure 22. Large Signal Transient Response for Various Supplies
1.5
Figure 25. Large Signal Transient Response for Various Supplies
1.5
CL = 9pF CL = 6pF
CL = 9pF
CL = 6pF
1.0
OUTPUT VOLTAGE (V)
1.0 CL = 4pF
OUTPUT VOLTAGE (V)
CL = 4pF 0.5
0.5
0
0
-0.5 VS = 5V G = +1 VOUT = 2V p-p TIME = 5ns/DIV
-0.5 VS = 5V G = +2 VOUT = 2V p-p TIME = 5ns/DIV
-1.0
-1.0
05708-031
-1.5
-1.5
Figure 23. Large Signal Transient Response for Various Capacitor Loads
4.0
Figure 26. Large Signal Transient Response for Various Capacitor Loads
4.0
CL = 9pF
CL = 6pF 3.5
OUTPUT VOLTAGE (V)
CL = 9pF
CL = 6pF
3.5
OUTPUT VOLTAGE (V)
CL = 4pF 3.0
CL = 4pF 3.0
2.5
2.5
2.0 VS = 5V G = +1 VOUT = 2V p-p TIME = 5ns/DIV
2.0 VS = 5V G = +2 VOUT = 2V p-p TIME = 5ns/DIV
05708-030
1.0
1.0
Figure 24. Large Signal Transient Response for Various Capacitor Loads
Figure 27. Large Signal Transient Response for Various Capacitor Loads
Rev. A | Page 9 of 16
05708-032
1.5
1.5
05708-033
05708-016
G = +1 VOUT = 2V p-p TIME = 5ns/DIV
1.5
-1.0
G = +2 VOUT = 2V p-p TIME = 5ns/DIV
1.5
OUTPUT VOLTAGE (V) +VS = 5V, -VS = 0V
VS = 5V
ADA4861-3
1800 1600 1400 VS = 5V G = +1 1400 1200 POSITIVE SLEW RATE POSITIVE SLEW RATE 1000 VS = 5V G = +2
SLEW RATE (V/s)
1200 1000 800 600 400
05708-036
SLEW RATE (V/s)
800 NEGATIVE SLEW RATE 600 400 200 0
NEGATIVE SLEW RATE
0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
INPUT VOLTAGE (V p-p)
INPUT VOLTAGE (V p-p)
Figure 28. Slew Rate vs. Input Voltage
700 600 500 700 600 500
Figure 31. Slew Rate vs. Input Voltage
VS = 5V G = +1 POSITIVE SLEW RATE
VS = 5V G = +2
POSITIVE SLEW RATE
SLEW RATE (V/s)
SLEW RATE (V/s)
NEGATIVE SLEW RATE 400 300 200 100 0
400 300 200 100 0
NEGATIVE SLEW RATE
05708-021
0
0.5
1.0
1.5
2.0
2.5
3.0
0
0.25
0.50
0.75
1.00
1.25
1.50
INPUT VOLTAGE (V p-p)
INPUT VOLTAGE (V p-p)
Figure 29. Slew Rate vs. Input Voltage
1.00 0.75 0.50 1.00 0.75 0.50
Figure 32. Slew Rate vs. Input Voltage
VIN
t = 0s
VS = 5V G = +2 VOUT = 2V p-p TIME = 5ns/DIV
SETTLING TIME (%)
0.25 0 -0.25 -0.50
05708-022
SETTLING TIME (%)
1V
1V 0.25 0 -0.25 -0.50
05708-020
-0.75 -1.00 t = 0s
VS = 5V G = +2 VOUT = 2V p-p TIME = 5ns/DIV
-0.75 -1.00 VIN
Figure 30. Settling Time Rising Edge
Figure 33. Settling Time Falling Edge
Rev. A | Page 10 of 16
05708-019
05708-018
200
ADA4861-3
1000 VS = 5V G = +2 0
0 -10 -20
VS = 5V, +5V G = +2 VOUT = 2V p-p
TRANSIMPEDANCE (k)
100 TRANSIMPEDANCE PHASE 10
-45
PHASE (Degrees)
CROSSTALK (dB)
-30 -40 -50 -60 -70 -80
-90
1
-135
05708-044
-90 -100 0.1 1 10 FREQUENCY (MHz) 100
0.1 0.01
0.1
1
10
100
-180 1000
1000
FREQUENCY (MHz)
Figure 34. Transimpedance and Phase vs. Frequency
0 -10
POWER SUPPLY REJECTION (dB)
Figure 37. Large Signal All-Hostile Crosstalk
0 -10 -20 -30 -40 -50 -60 -70 0.01
VS = 5V G = +2
COMMON-MODE REJECTION (dB)
VS = 5V G = +2 VIN = 2V p-p
-20 -30 -40 -PSR -50 -60 -70 -80 0.01 +PSR
05708-023
0.1
1
10
100
1000
0.1
1
10
100
1000
FREQUENCY (MHz)
FREQUENCY (MHz)
Figure 35. Power Supply Rejection vs. Frequency
6 5 5.5 5.0
Figure 38. Common-Mode Rejection vs. Frequency
INPUT VOLTAGE x 2
OUTPUT AND INPUT VOLTAGE (V)
3 2 1 0 -1 -2 -3 -4
OUTPUT VOLTAGE
OUTPUT AND INPUT VOLTAGE (V)
4
VS = 5V G = +2 f = 1MHz
INPUT VOLTAGE x 2
4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 -0.5 0 100 200 300 400
VS = 5V G = +2 f = 1MHz
OUTPUT VOLTAGE
05708-035
-5 -6 0 100 200 300 400 500 600 700 800 900
1000
500
600
700
800
900
1000
TIME (ns)
TIME (ns)
Figure 36. Output Overdrive Recovery
Figure 39. Output Overdrive Recovery
Rev. A | Page 11 of 16
05708-034
05708-045
05708-024
ADA4861-3
35 30 25 20 15 10 5 0 10 VS = 5V, +5V 60 VS = 5V, +5V
INPUT VOLTAGE NOISE (nV/ Hz)
INPUT CURRENT NOISE (pA/ Hz)
50
40
30
INVERTING INPUT
20 NONINVERTING INPUT 10
05708-053
05708-052
100
1k FREQUENCY (Hz)
10k
100k
0 10
100
1k FREQUENCY (Hz)
10k
100k
Figure 40. Input Voltage Noise vs. Frequency
19
20 19
TOTAL SUPPLY CURRENT (mA)
Figure 43. Input Current Noise vs. Frequency
TOTAL SUPPLY CURRENT (mA)
18
18 17
VS = 5V
17
VS = +5V 16 15 14
05708-025
16
15
05708-043
13 12 -40
14
4
5
6
7
8
9
10
11
12
-25
-10
5
20
35
50
65
80
95
110
125
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
Figure 41. Total Supply Current vs. Supply Voltage
25 20 15
Figure 44. Total Supply Current at Various Supplies vs. Temperature
20 15
INPUT BIAS CURRENT (A)
10
INPUT VOS (mV)
10 VS = 5V 5 0 -5 -10 -15 -5 VS = +5V
5 0 -5 -10 -15
VS = 5V
VS = +5V
05708-046
-20 -25 -5 -4 -3 -2 -1 0 VCM (V) 1 2 3 4 5
-4
-3
-2
-1
0
1
2
3
4
5
OUTPUT VOLTAGE (V)
Figure 42. Input VOS vs. Common-Mode Voltage
Figure 45. Input Bias Current vs. Output Voltage
Rev. A | Page 12 of 16
05708-026
ADA4861-3 APPLICATIONS
GAIN CONFIGURATIONS
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. Table 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
Gain +1 -1 +2 +5 +10
1
20 MHz ACTIVE LOW-PASS FILTER
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.
R11 210k R12 301
- R1 562 R2 562 C1 10pF C2 10pF U1 OP AMP + OUT
VIN
RF () 499 301 301 200 200
RG () N/A 301 301 49.9 22.1
-3 dB SS BW (MHz) 730 350 370 180 80
Large Signal 0.1 dB Flatness 90 60 100 30 15
R9 210
R10 301
- R3 562 R4 562 C3 10pF C4 10pF U2 OP AMP + OUT
Conditions: VS = 5 V, TA = 25C, RL = 150 .
Figure 46 and Figure 47 show the typical noninverting and inverting configurations and recommended bypass capacitor values.
+VS 10F
R7 210
R8 301
-
0.1F VIN +
R5 562
R6 562 C5 10pF C6 10pF
U3 OP AMP +
OUT
VOUT
ADA4861-3
- 0.1F 10F RF RG -VS
VOUT
Figure 48. 28 MHz, 6-Pole Low-Pass Filter
Figure 46. Noninverting Gain
RF +VS 10F 0.1F VIN RG -
05708-005
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.
30 20 10 0
MAGNITUDE (dB)
-10 -20 -30 -40
ADA4861-3
+ 0.1F 10F
VOUT
-50 -60
05708-006
-VS
-70
1
10 FREQUENCY (MHz)
100
200
Figure 47. Inverting Gain
Figure 49. 20 MHz Low-Pass Filter Frequency Response
Rev. A | Page 13 of 16
05708-047
05708-007
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 . The amplifier inputs are terminated with shunt 75 resistors, and the outputs have series 75 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 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.
10F 0.1F
NORMALIZED GAIN (dB)
+VS RG 301 RF 301 10F 75 75 CABLE VOUT1 75 75 CABLE VOUT2 75 0.1F
05708-004
0.1F
-
ADA4861-3
+
75 CABLE VIN 75 -VS 10F
75
Figure 51. Video Driver Schematic for Two Video Loads
0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -0.7 -0.8 -0.9 1 10 FREQUENCY (MHz) 100
05708-010
VS = 5V RL = 75 VOUT = 2V p-p
+VS PD1 PD2 PD3
3 2 1 4
VIN (R) 75
5 7 6
75
VOUT (R)
RG 301 VIN (G) 75
10
RF 301 75
8 9
400
VOUT (G)
Figure 52. Large Signal Frequency Response for Various Supplies, RL = 75
RG 301 VIN (B) 75
12
RF 301 75
14 13
POWER-DOWN PINS
VOUT (B)
RG 301
RF 301
11
0.1F 10F -VS
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.
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.
05708-003
Rev. A | Page 14 of 16
ADA4861-3
SINGLE-SUPPLY OPERATION
The ADA4861-3 can also be operated from a single power supply. 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/3502/avoiding/.
+5V C2 1F C3 2.2F
POWER SUPPLY BYPASSING
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 F to 47 F 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 F 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.
+5V
R2 50k R3 1k
R4 50k
C4 0.01F
LAYOUT
C6 220F R5 75 VOUT R6 75
VIN R1 50 C1 22F
ADA4861-3
-VS
05708-054
C5 22F
Figure 53. Single-Supply Video Driver Schematic
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: www.analog.com and www.analog.com/library/analogDialogue/archives/3909/layout.html.
Rev. A | Page 15 of 16
ADA4861-3 OUTLINE DIMENSIONS
8.75 (0.3445) 8.55 (0.3366) 4.00 (0.1575) 3.80 (0.1496)
14 1 8 7
6.20 (0.2441) 5.80 (0.2283)
0.25 (0.0098) 0.10 (0.0039) COPLANARITY 0.10
1.27 (0.0500) BSC
1.75 (0.0689) 1.35 (0.0531)
0.50 (0.0197) x 45 0.25 (0.0098)
0.51 (0.0201) 0.31 (0.0122)
SEATING PLANE
8 0.25 (0.0098) 0 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067)
COMPLIANT TO JEDEC STANDARDS MS-012-AB 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.
Figure 54. 14-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-14) Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model ADA4861-3YRZ 1 ADA4861-3YRZ-RL1 ADA4861-3YRZ-RL71
1
Temperature Range -40C to +105C -40C to +105C -40C to +105C
Package Description 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N
Package Option R-14 R-14 R-14
Ordering Quantity 1 2,500 1,000
Z = Pb-free part.
(c)2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05708-0-3/06(A)
Rev. A | Page 16 of 16

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