High Speed, Low Cost, Triple Op Amp ADA4861-3 PIN CONFIGURATION 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 POWER DOWN 1 1 14 OUT 2 POWER DOWN 2 2 13 –IN 2 POWER DOWN 3 3 +VS 4 12 +IN 2 ADA4861-3 11 –VS +IN 1 5 10 +IN 3 –IN 1 6 9 –IN 3 OUT 1 7 8 OUT 3 05708-001 FEATURES Figure 1. APPLICATIONS Consumer video Professional video Broadband video ADC buffers Active filters GENERAL DESCRIPTION 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. G = +2 VOUT = 2V p-p RF = RG = 301Ω 6.0 5.9 5.8 VS = ±5V 5.7 VS = +5V 5.6 5.5 5.4 5.3 05708-011 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. 6.1 CLOSED-LOOP GAIN (dB) 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. 5.2 5.1 0.1 1 10 100 1000 FREQUENCY (MHz) 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 ©2006 Analog Devices, Inc. All rights reserved. ADA4861-3 TABLE OF CONTENTS Features .............................................................................................. 1 Gain Configurations .................................................................. 13 Applications....................................................................................... 1 20 MHz Active Low-Pass Filter ................................................ 13 Pin Configuration............................................................................. 1 RGB Video Driver ...................................................................... 14 General Description ......................................................................... 1 Driving Two Video Loads ......................................................... 14 Revision History ............................................................................... 2 POWER-DOWN Pins ............................................................... 14 Specifications..................................................................................... 3 Single-Supply Operation ........................................................... 15 Absolute Maximum Ratings............................................................ 5 Power Supply Bypassing ............................................................ 15 Thermal Resistance ...................................................................... 5 Layout .......................................................................................... 15 ESD Caution.................................................................................. 5 Outline Dimensions ....................................................................... 16 Typical Performance Characteristics ............................................. 6 Ordering Guide .......................................................................... 16 Applications..................................................................................... 13 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 = 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 DYNAMIC PERFORMANCE –3 dB Bandwidth 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 Conditions Min Typ Max Unit 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 350 145 560 85 590 480 12/13 MHz MHz MHz MHz V/μs V/μs ns fC = 1 MHz, VO = 2 V p-p fC = 5 MHz, VO = 2 V p-p f = 100 kHz f = 100 kHz, +IN/−IN −81/−89 −69/−76 3.8 1.7/5.5 0.02 0.03 −65 dBc dBc nV/√Hz pA/√Hz % Degrees dB Amplifier 1 and Amplifier 2 driven, Amplifier 3 output measured, f = 1 MHz +IN −IN +IN G = +1 VCM = 2 V to 3 V −13 −2 −8 400 −0.9 −0.8 +2.3 620 −54 14 85 1.5 1.2 to 3.8 −56.5 MΩ Ω pF V dB 0.6 1.8 −3 115 200 3.5 V V μA μA ns μs 55/100 1.1 to 3.9 0.85 to 4.15 65 ns V V mA Enabled Power down Enabled Power down VIN = +2.25 V to −0.25 V RL = 150 Ω RL = 1 kΩ Sinking and sourcing Enabled POWER DOWN pins = +VS +VS = 4 V to 6 V, −VS = 0 V Rev. A | Page 3 of 16 1.2 to 3.8 0.9 to 4.1 5 12.5 −60 16.1 0.2 −64 +13 +1 +13 12 18.5 0.33 mV μA μA kΩ V mA mA dB ADA4861-3 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 DYNAMIC PERFORMANCE –3 dB Bandwidth 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 Conditions Min Typ Max Unit 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 370 210 730 100 910 680 12/13 MHz MHz MHz MHz V/μs V/μs ns fC = 1 MHz, VO = 2 V p-p fC = 5 MHz, VO = 2 V p-p f = 100 kHz f = 100 kHz, +IN/−IN −85/−99 −73/−86 3.8 1.7/5.5 0.01 0.02 −65 dBc dBc nV/√Hz pA/√Hz % Degrees dB Amplifier 1 and Amplifier 2 driven, Amplifier 3 output measured, f = 1 MHz +IN −IN +IN G = +1 VCM = ±2 V −13 −2 −8 500 −0.1 −0.7 +2.9 720 −55 15 90 1.5 −3.7 to +3.7 −58 MΩ Ω pF V dB −4.4 −3.2 −3 250 200 3.5 V V μA μA ns μs 30/90 −3.1 to +3.65 ±4.05 100 ns V V mA Enabled Power down Enabled Power down VIN = ±3.0 V RL = 150 Ω RL = 1 kΩ Sinking and sourcing 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 Rev. A | Page 4 of 16 ±2 ±3.9 5 13.5 −63 −59 17.9 0.3 −66 −62 +13 +1 +13 12 20.5 0.5 mV μA μA kΩ V mA mA dB dB ADA4861-3 ABSOLUTE MAXIMUM RATINGS Table 3. 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). Rating 12.6 V See Figure 3 −VS + 1 V to +VS − 1 V ±VS −65°C to +125°C −40°C to +105°C JEDEC J-STD-20 150°C PD = Quiescent Power + (Total Drive Power − Load Power) ⎛V V ⎞ V 2 PD = (VS × I S ) + ⎜ S × OUT ⎟ – OUT RL ⎠ RL ⎝ 2 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. Table 4. Thermal Resistance Package Type 14-lead SOIC_N θJA 90 Unit °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. RMS output voltages should be considered. 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. 2.5 2.0 1.5 1.0 0.5 05708-002 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. MAXIMUM POWER DISSIPATION (W) Parameter Supply Voltage Power Dissipation Common-Mode Input Voltage Differential Input Voltage Storage Temperature Operating Temperature Range Lead Temperature Junction Temperature 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 Ω and CL = 4 pF, unless otherwise noted. VS = ±5V VOUT = 0.2V p-p 1 G = +1, RF = 499Ω –2 –3 G = +2, RF = RG = 301Ω G = –1, RF = RG = 301Ω G = +5, RF = 200Ω, RG = 49.9Ω –4 –1 G = +2, RF = RG = 301Ω –2 G = –1, RF = RG = 301Ω –3 G = +5, RF = 200Ω, RG = 49.9Ω –4 G = +10, RF = 200Ω, RG = 22.1Ω G = +10, RF = 200Ω, RG = 22.1Ω –5 05708-038 –5 –6 0.1 1 10 100 –6 0.1 1000 1 FREQUENCY (MHz) G = –1, RF = RG = 301Ω 0 1000 VS = 5V VOUT = 2V p-p G = +5, RF = 200Ω, RG = 49.9Ω –1 G = +5, RF = 200Ω, RG = 49.9Ω –2 G = +1, RF = 499Ω NORMALIZED GAIN (dB) 0 G = +2, RF = RG = 301Ω –3 –4 –5 G = +10, RF = 200Ω, RG = 22.1Ω –6 0.1 1 10 100 G = +1, RF = 499Ω –1 –2 G = +2, RF = RG = 301Ω –3 G = +10, RF = 200Ω, RG = 22.1Ω –4 –5 05708-028 NORMALIZED GAIN (dB) 100 Figure 7. Small Signal Frequency Response for Various Gains 1 VS = ±5V VOUT = 2V p-p 10 FREQUENCY (MHz) Figure 4. Small Signal Frequency Response for Various Gains 1 G = +1, RF = 499Ω 05708-037 –1 VS = 5V VOUT = 0.2V p-p 0 NORMALIZED GAIN (dB) NORMALIZED GAIN (dB) 0 G = –1, RF = RG = 301Ω –6 0.1 1000 1 FREQUENCY (MHz) 1000 Figure 8. Large Signal Frequency Response for Various Gains 7 G = +2 VOUT = 2V p-p RF = RG = 301Ω 6.0 100 FREQUENCY (MHz) Figure 5. Large Signal Frequency Response for Various Gains 6.1 10 05708-027 1 VS = ±5V G = +2 VOUT = 1V p-p 6 CLOSED-LOOP GAIN (dB) 5.8 VS = ±5V 5.7 VS = +5V 5.6 5.5 5.4 5 VOUT = 2V p-p 4 3 VOUT = 4V p-p 2 5.3 1 10 100 0 0.1 1000 05708-029 5.2 5.1 0.1 1 05708-011 CLOSED-LOOP GAIN (dB) 5.9 1 10 100 1000 FREQUENCY (MHz) FREQUENCY (MHz) Figure 6. Large Signal 0.1 dB Flatness Figure 9. Large Signal Frequency Response for Various Output Levels Rev. A | Page 6 of 16 ADA4861-3 7 7 RF = 301Ω 6 RF = 301Ω 6 RF = 499Ω 4 RF = 604Ω 3 2 VS = ±5V G = +2 RG = RF VOUT = 0.2V p-p 1 0 0.1 1 10 100 5 RF = 499Ω 4 RF = 604Ω 3 2 1 0 0.1 1000 VS = ±5V G = +2 RF = RG VOUT = 2V p-p 1 FREQUENCY (MHz) –40 –50 –80 VOUT = 2V p-p HD3 VOUT = 3V p-p HD3 1 VOUT = 2V p-p HD2 –70 VOUT = 3V p-p HD3 –80 VOUT = 2V p-p HD3 –90 –100 50 10 VOUT = 3V p-p HD2 –60 1 Figure 11. Harmonic Distortion vs. Frequency Figure 14. Harmonic Distortion vs. Frequency –40 VS = 5V G = +2 VOUT = 2V p-p HD3 –50 –50 VOUT = 2V p-p HD2 DISTORTION (dBc) –60 –70 –80 –90 VOUT = 1V p-p HD2 VOUT = 1V p-p HD3 1 10 VOUT = 2V p-p HD2 –70 VOUT = 1V p-p HD2 –80 –90 VOUT = 1V p-p HD3 –100 05708-048 –100 VOUT = 2V p-p HD3 –110 50 FREQUENCY (MHz) 05708-050 VS = 5V G = +1 –60 50 10 FREQUENCY (MHz) FREQUENCY (MHz) –40 05708-051 DISTORTION (dBc) VOUT = 2V p-p HD2 –70 05708-049 DISTORTION (dBc) VOUT = 3V p-p HD2 –90 DISTORTION (dBc) 1000 VS = ±5V G = +2 VS = ±5V G = +1 –60 –110 100 Figure 13. Large Signal Frequency Response vs. RF –50 –100 10 FREQUENCY (MHz) Figure 10. Small Signal Frequency Response vs. RF –40 05708-013 CLOSED-LOOP GAIN (dB) RF = 402Ω 5 05708-012 CLOSED-LOOP GAIN (dB) RF = 402Ω 1 10 FREQUENCY (MHz) Figure 15. Harmonic Distortion vs. Frequency Figure 12. Harmonic Distortion vs. Frequency Rev. A | Page 7 of 16 50 ADA4861-3 200 200 2.7 2.7 2.5 –100 2.4 G = +1 VOUT = 0.2V p-p TIME = 5ns/DIV 2.3 0 2.5 –100 2.4 G = +2 VOUT = 0.2V p-p TIME = 5ns/DIV –200 Figure 16. Small Signal Transient Response for Various Supplies Figure 19. Small Signal Transient Response for Various Supplies 200 200 CL = 9pF CL = 9pF OUTPUT VOLTAGE (mV) 100 CL = 4pF 0 –100 VS = ±5V G = +1 VOUT = 0.2V p-p TIME = 5ns/DIV –200 05708-040 OUTPUT VOLTAGE (mV) CL = 6pF Figure 17. Small Signal Transient Response for Various Capacitor Loads 2.7 CL = 6pF 0 –100 Figure 20. Small Signal Transient Response for Various Capacitor Loads 2.7 CL = 9pF OUTPUT VOLTAGE (V) CL = 4pF 2.5 Figure 18. Small Signal Transient Response for Various Capacitor Loads CL = 4pF 2.6 CL = 6pF 2.5 2.4 VS = 5V G = +1 VOUT = 0.2V p-p TIME = 5ns/DIV 05708-039 2.3 VS = ±5V G = +2 VOUT = 0.2V p-p TIME = 5ns/DIV –200 CL = 9pF 2.6 2.4 CL = 4pF 100 CL = 6pF OUTPUT VOLTAGE (V) 2.3 2.3 VS = 5V G = +2 VOUT = 0.2V p-p TIME = 5ns/DIV 05708-041 –200 VS = ±5V OUTPUT VOLTAGE (V) +VS = 5V, –VS = 0V 0 2.6 05708-014 VS = ±5V 100 05708-042 2.6 OUTPUT VOLTAGE (mV) ±VS = 5V 100 OUTPUT VOLTAGE (V) +VS = 5V, –VS = 0V VS = +5V 05708-015 OUTPUT VOLTAGE (mV) ±VS = 5V VS = +5V Figure 21. Small Signal Transient Response for Various Capacitor Loads Rev. A | Page 8 of 16 ADA4861-3 1.0 3.0 0 2.5 –0.5 2.0 G = +1 VOUT = 2V p-p TIME = 5ns/DIV 1.0 VS = ±5V G = +1 VOUT = 2V p-p TIME = 5ns/DIV CL = 9pF CL = 6pF OUTPUT VOLTAGE (V) CL = 4pF 0 –0.5 Figure 26. Large Signal Transient Response for Various Capacitor Loads 4.0 CL = 9pF VS = ±5V G = +2 VOUT = 2V p-p TIME = 5ns/DIV –1.5 CL = 6pF CL = 9pF CL = 6pF 3.5 3.5 OUTPUT VOLTAGE (V) CL = 4pF 3.0 2.5 2.0 VS = 5V G = +1 VOUT = 2V p-p TIME = 5ns/DIV CL = 4pF 3.0 2.5 2.0 1.5 05708-030 OUTPUT VOLTAGE (V) 1.0 0.5 –1.0 05708-031 OUTPUT VOLTAGE (V) CL = 4pF Figure 23. Large Signal Transient Response for Various Capacitor Loads 1.0 1.5 G = +2 VOUT = 2V p-p TIME = 5ns/DIV 1.0 –1.5 1.5 2.0 1.5 CL = 9pF CL = 6pF –0.5 4.0 –0.5 Figure 25. Large Signal Transient Response for Various Supplies 0 –1.0 2.5 –1.5 1.0 0.5 3.0 0 –1.0 Figure 22. Large Signal Transient Response for Various Supplies 1.5 VS = ±5V 0.5 05708-033 –1.5 1.5 3.5 Figure 24. Large Signal Transient Response for Various Capacitor Loads 1.0 VS = 5V G = +2 VOUT = 2V p-p TIME = 5ns/DIV 05708-032 –1.0 4.0 OUTPUT VOLTAGE (V) +VS = 5V, –VS = 0V 3.5 VS = +5V 05708-016 VS = ±5V 0.5 1.5 OUTPUT VOLTAGE (V) ±VS = 5V OUTPUT VOLTAGE (V) ±VS = 5V 1.0 4.0 OUTPUT VOLTAGE (V) +VS = 5V, –VS = 0V VS = +5V 05708-017 1.5 Figure 27. Large Signal Transient Response for Various Capacitor Loads Rev. A | Page 9 of 16 ADA4861-3 1800 1600 VS = ±5V G = +2 1200 POSITIVE SLEW RATE 1400 POSITIVE SLEW RATE 1000 SLEW RATE (V/µs) SLEW RATE (V/µs) 1400 VS = ±5V G = +1 1200 1000 800 NEGATIVE SLEW RATE 600 800 NEGATIVE SLEW RATE 600 400 400 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 05708-018 0 5.0 0 0.25 0.50 0.75 INPUT VOLTAGE (V p-p) Figure 28. Slew Rate vs. Input Voltage 700 700 POSITIVE SLEW RATE VS = 5V G = +2 2.25 2.50 POSITIVE SLEW RATE 300 200 100 100 0 0.5 1.0 1.5 2.5 2.0 0 3.0 05708-019 SLEW RATE (V/µs) NEGATIVE SLEW RATE 0 0.25 0.50 INPUT VOLTAGE (V p-p) 1.00 0.75 1.25 1.00 1.50 INPUT VOLTAGE (V p-p) Figure 29. Slew Rate vs. Input Voltage Figure 32. Slew Rate vs. Input Voltage 1.00 VIN 0.75 t = 0s 0.75 VS = ±5V G = +2 VOUT = 2V p-p TIME = 5ns/DIV 0.50 SETTLING TIME (%) 1V 0.25 0 –0.25 –0.50 1V 0.25 0 –0.25 –0.50 –0.75 t = 0s VS = ±5V G = +2 VOUT = 2V p-p TIME = 5ns/DIV –0.75 05708-022 SETTLING TIME (%) 2.00 400 200 05708-021 SLEW RATE (V/µs) NEGATIVE SLEW RATE 300 –1.00 1.75 500 400 0.50 1.50 600 500 0 1.25 Figure 31. Slew Rate vs. Input Voltage VS = 5V G = +1 600 1.00 INPUT VOLTAGE (V p-p) –1.00 Figure 30. Settling Time Rising Edge VIN Figure 33. Settling Time Falling Edge Rev. A | Page 10 of 16 05708-020 0 200 05708-036 200 ADA4861-3 1000 VS = ±5V G = +2 0 0 VS = ±5V, +5V G = +2 VOUT = 2V p-p –10 –90 CROSSTALK (dB) PHASE 10 PHASE (Degrees) TRANSIMPEDANCE –30 –40 –50 –60 –70 –135 1 0.1 1 10 05708-024 –180 1000 100 05708-044 –80 0.1 0.01 –90 –100 0.1 1 10 –20 –30 –40 –PSR –50 +PSR –60 05708-023 –70 –80 0.01 0.1 1 10 100 VS = ±5V G = +2 VIN = 2V p-p –10 –20 –30 –40 –50 –60 05708-045 COMMON-MODE REJECTION (dB) POWER SUPPLY REJECTION (dB) 0 VS = ±5V G = +2 –10 –70 0.01 1000 0.1 1 5.5 VS = ±5V G = +2 f = 1MHz 1 0 –1 –2 –3 05708-035 –4 –5 0 100 200 300 400 500 600 700 800 900 4.5 OUTPUT VOLTAGE 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 05708-034 OUTPUT VOLTAGE 2 –6 1000 VS = 5V G = +2 f = 1MHz INPUT VOLTAGE × 2 5.0 OUTPUT AND INPUT VOLTAGE (V) INPUT VOLTAGE × 2 5 3 100 Figure 38. Common-Mode Rejection vs. Frequency Figure 35. Power Supply Rejection vs. Frequency 4 10 FREQUENCY (MHz) FREQUENCY (MHz) 6 1000 Figure 37. Large Signal All-Hostile Crosstalk Figure 34. Transimpedance and Phase vs. Frequency 0 100 FREQUENCY (MHz) FREQUENCY (MHz) OUTPUT AND INPUT VOLTAGE (V) TRANSIMPEDANCE (kΩ) –20 –45 100 0 –0.5 1000 TIME (ns) 0 100 200 300 400 500 600 700 800 TIME (ns) Figure 36. Output Overdrive Recovery Figure 39. Output Overdrive Recovery Rev. A | Page 11 of 16 900 1000 ADA4861-3 60 30 25 20 15 10 05708-052 5 0 10 100 1k 10k VS = ±5V, +5V 50 40 30 INVERTING INPUT 20 NONINVERTING INPUT 10 05708-053 VS = ±5V, +5V INPUT CURRENT NOISE (pA/ Hz) INPUT VOLTAGE NOISE (nV/ Hz) 35 0 10 100k 100 1k FREQUENCY (Hz) 10k 100k FREQUENCY (Hz) Figure 40. Input Voltage Noise vs. Frequency Figure 43. Input Current Noise vs. Frequency 19 20 TOTAL SUPPLY CURRENT (mA) 17 16 15 4 5 6 7 8 9 10 11 17 VS = +5V 16 15 14 12 –40 12 05708-025 14 VS = ±5V 18 13 05708-043 TOTAL SUPPLY CURRENT (mA) 19 18 –25 –10 5 SUPPLY VOLTAGE (V) 20 35 50 65 80 95 110 125 TEMPERATURE (°C) Figure 41. Total Supply Current vs. Supply Voltage Figure 44. Total Supply Current at Various Supplies vs. Temperature 25 20 20 15 5 VS = +5V 0 –5 –10 –15 –20 –25 –5 –4 –3 –2 –1 0 1 2 3 4 5 VCM (V) 10 VS = ±5V 5 VS = +5V 0 –5 –10 –15 –5 05708-026 VS = ±5V 05708-046 INPUT VOS (mV) 10 INPUT BIAS CURRENT (μA) 15 –4 –3 –2 –1 0 1 2 3 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 4 5 ADA4861-3 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. Table 5 provides a convenient reference for quickly determining the feedback and gain set resistor values and bandwidth for common gain configurations. 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 210kΩ – R1 562Ω VIN C1 10pF RG (Ω) 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 C2 10pF R9 210Ω – R3 562Ω U2 OP AMP + R4 562Ω C3 10pF 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. +VS R10 301Ω OUT C4 10pF R7 210Ω R8 301Ω 10µF – 0.1µF VIN R5 562Ω + ADA4861-3 – C5 10pF VOUT 0.1µF VOUT C6 10pF 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. –VS 05708-005 RG OUT Figure 48. 28 MHz, 6-Pole Low-Pass Filter 10µF RF U3 OP AMP + R6 562Ω 05708-007 1 RF (Ω) 499 301 301 200 200 OUT U1 OP AMP + R2 562Ω Table 5. Recommended Values and Frequency Performance1 Gain +1 −1 +2 +5 +10 R12 301Ω Figure 46. Noninverting Gain 30 20 RF +VS 10 10µF – ADA4861-3 VOUT –10 –20 –30 –40 + 0.1µF –50 –60 10µF –VS 05708-047 RG 05708-006 VIN MAGNITUDE (dB) 0 0.1µF –70 1 10 100 FREQUENCY (MHz) Figure 47. Inverting Gain Figure 49. 20 MHz Low-Pass Filter Frequency Response Rev. A | Page 13 of 16 200 ADA4861-3 RF 301Ω RGB VIDEO DRIVER RG 301Ω PD3 4 1 5 75Ω VIN (G) 75Ω 7 6 RG 301Ω VIN (B) RG 301Ω VOUT2 75Ω 0.1µF VIN 75Ω 10µF –VS Figure 51. Video Driver Schematic for Two Video Loads 0.1 VS = ±5V RL = 75Ω VOUT = 2V p-p 0 VOUT (R) –0.2 –0.3 –0.4 –0.5 –0.6 –0.7 –0.9 75Ω 8 1 10 100 400 FREQUENCY (MHz) VOUT (G) Figure 52. Large Signal Frequency Response for Various Supplies, RL = 75 Ω POWER-DOWN PINS RF 301Ω 12 75Ω 75Ω CABLE –0.8 9 RG 301Ω 75Ω + RF 301Ω 10 75Ω VOUT1 75Ω 05708-010 VIN (R) 2 – 75Ω CABLE NORMALIZED GAIN (dB) 0.1µF 3 75Ω CABLE –0.1 10µF PD1 PD2 75Ω 0.1µF ADA4861-3 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. +VS 10µF +VS 05708-004 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). 75Ω 14 13 VOUT (B) RF 301Ω 11 10µF –VS 05708-003 0.1µF 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. Rev. A | Page 14 of 16 ADA4861-3 SINGLE-SUPPLY OPERATION POWER SUPPLY BYPASSING 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/. 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. +5V R2 50kΩ C3 2.2µF R4 50kΩ C4 0.01µF R3 1kΩ C6 220µF VIN R1 50Ω LAYOUT C1 22µF R5 75Ω VOUT R6 75Ω ADA4861-3 C5 22µF –VS Figure 53. Single-Supply Video Driver Schematic 05708-054 +5V C2 1µF 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) 0.25 (0.0098) 0.10 (0.0039) 14 8 1 7 1.27 (0.0500) BSC COPLANARITY 0.10 0.51 (0.0201) 0.31 (0.0122) 6.20 (0.2441) 5.80 (0.2283) 1.75 (0.0689) 1.35 (0.0531) SEATING PLANE 0.50 (0.0197) × 45° 0.25 (0.0098) 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 –40°C to +105°C –40°C to +105°C –40°C to +105°C Package Description 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N 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) Rev. A | Page 16 of 16 Package Option R-14 R-14 R-14 Ordering Quantity 1 2,500 1,000