Low Cost CMOS, High Speed, Rail-to-Rail Amplifiers ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 CONNECTION DIAGRAMS APPLICATIONS Automotive infotainment systems Automotive driver assistance systems Imaging Consumer video Active filters Coaxial cable drivers Clock buffers Photodiode preamp Contact image sensor and buffers 8 NC 7 +VS +IN 3 6 OUT -VS 4 5 NC 08054-026 NC 1 -IN 2 NC = NO CONNECT Figure 1. 8-Lead SOIC_N (R-8) ADA4891-1 OUT 1 5 +VS 4 -IN -VS 2 +IN 3 Figure 2. 5-Lead SOT-23 (RJ-5) ADA4891-2 OUT1 1 8 +VS -IN1 2 7 OUT2 +IN1 3 6 -IN2 -VS 4 5 +IN2 NC = NO CONNECT Figure 3. 8-Lead SOIC_N (R-8) and 8-Lead MSOP (RM-8) The ADA4891-1 (single), ADA4891-2 (dual), ADA4891-3 (triple), and ADA4891-4 (quad) are CMOS, high speed amplifiers that offer high performance at a low cost. The amplifiers feature true single-supply capability, with an input voltage range that extends 300 mV below the negative rail. In spite of their low cost, the ADA4891-1/ADA4891-2/ADA4891-3/ ADA4891-4 family provides high performance and versatility. The rail-to-rail output stage enables the output to swing to within 50 mV of each rail, enabling maximum dynamic range. The ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 family of amplifiers is ideal for imaging applications, such as consumer video, CCD buffers, and contact image sensor and buffers. Low distortion and fast settling time also make them ideal for active filter applications. The ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 are available in a wide variety of packages. The ADA4891-1 is available in 8-lead SOIC and 5-lead SOT-23 packages. The ADA4891-2 is available in 8-lead SOIC and 8-lead MSOP packages. The ADA4891-3 and ADA4891-4 are available in 14-lead SOIC and PD1 1 14 OUT2 PD2 2 13 -IN2 PD3 3 12 +IN2 +VS 4 11 -VS +IN1 5 10 +IN3 -IN1 6 9 -IN3 OUT1 7 8 OUT3 08054-073 ADA4891-3 GENERAL DESCRIPTION Rev. F ADA4891-1 08054-001 Qualified for automotive applications High speed and fast settling -3 dB bandwidth: 220 MHz (G = +1) Slew rate: 170 V/s Settling time to 0.1%: 28 ns Video specifications (G = +2, RL = 150 ) 0.1 dB gain flatness: 25 MHz Differential gain error: 0.05% Differential phase error: 0.25 Single-supply operation Wide supply range: 2.7 V to 5.5 V Output swings to within 50 mV of supply rails Low distortion: 79 dBc SFDR at 1 MHz Linear output current: 125 mA at -40 dBc Low power: 4.4 mA per amplifier 08054-027 FEATURES Figure 4. 14-Lead SOIC_N (R-14) and 14-Lead TSSOP (RU-14) ADA4891-4 OUT4 OUT1 1 14 -IN1 2 13 -IN4 +IN1 3 12 +IN4 +VS 4 11 -VS +IN2 5 10 +IN3 -IN2 6 9 -IN3 OUT2 7 8 OUT3 08054-074 Data Sheet Figure 5. 14-Lead SOIC_N (R-14) and 14-Lead TSSOP (RU-14) 14-lead TSSOP packages. The amplifiers are specified to operate over the extended temperature range of -40C to +125C. Document Feedback 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 (c)2010-2015 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Effect of RF on 0.1 dB Gain Flatness ........................................ 17 Applications ....................................................................................... 1 Driving Capacitive Loads .......................................................... 18 General Description ......................................................................... 1 Terminating Unused Amplifiers .............................................. 19 Connection Diagrams ...................................................................... 1 Disable Feature (ADA4891-3 Only) ......................................... 19 Revision History ............................................................................... 3 Single-Supply Operation ........................................................... 19 Specifications..................................................................................... 4 Video Reconstruction Filter ...................................................... 20 5 V Operation ............................................................................... 4 Multiplexer .................................................................................. 20 3 V Operation ............................................................................... 5 Layout, Grounding, and Bypassing .............................................. 21 Absolute Maximum Ratings ............................................................ 7 Power Supply Bypassing ............................................................ 21 Maximum Power Dissipation ..................................................... 7 Grounding ................................................................................... 21 ESD Caution .................................................................................. 7 Input and Output Capacitance ................................................. 21 Typical Performance Characteristics ............................................. 8 Input-to-Output Coupling ........................................................ 21 Applications Information .............................................................. 16 Leakage Currents ........................................................................ 21 Using the ADA4891-1/ADA4891-2/ADA4891-3/ ADA4891-4 ................................................................................. 16 Outline Dimensions ....................................................................... 22 Wideband, Noninverting Gain Operation .............................. 16 Automotive Products ................................................................. 24 Ordering Guide .......................................................................... 24 Wideband, Inverting Gain Operation ..................................... 16 Recommended Values................................................................ 16 Rev. F | Page 2 of 24 Data Sheet ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 REVISION HISTORY 9/15--Rev. E to Rev. F Changes to Features .......................................................................... 1 Moved Revision History Section ..................................................... 3 Changes to Table 1 ............................................................................ 4 Changes to Table 2 ............................................................................ 5 Changes to Figure 7 and Figure 10 ................................................. 8 Changes to Figure 15 and Figure 18 ............................................... 9 Changes to Figure 19, Figure 21, and Figure 22 ..........................10 Changes to Figure 25 and Figure 29 .............................................11 Changes to Figure 32, Figure 33, and Figure 36 ..........................12 Change to Figure 47 ........................................................................14 Changes to Ordering Guide ...........................................................24 Change to Automotive Products Section .....................................24 3/13--Rev. D to Rev. E Change to Features Section .............................................................. 1 Changes to DC Performance Parameter, Table 1 .......................... 3 Changes to DC Performance Parameter, Table 2 .......................... 4 Changes to Ordering Guide ...........................................................23 Changes to Automotive Products Section ...................................23 3/12--Rev. C to Rev. D Added ADA4891-1W and ADA4891-2W ........................ Universal Changes to Features Section and Applications Section ............... 1 Changes to Input Offset Voltage, Input Bias Current, and OpenLoop Gain Parameters, Table 1........................................................ 4 Changes to Input Offset Voltage, Input Bias Current, and OpenLoop Gain Parameters, Table 2........................................................ 5 Changes to Ordering Guide ...........................................................23 Added Automotive Products Section ...........................................23 9/10--Rev. B to Rev. C Changes to Figure 23 and Figure 24 ............................................... 9 7/10--Rev. A to Rev. B Added ADA4891-3 and ADA4891-4 ............................... Universal Added 14-Lead SOIC and 14-Lead TSSOP Packages ... Universal Deleted Figure 4; Renumbered Figures Sequentially ................... 1 Changes to Features Section and General Description Section.. 1 Added Figure 4 and Figure 5 ........................................................... 1 Changes to Table 1 ............................................................................ 3 Changes to Table 2 ............................................................................ 4 Changes to Maximum Power Dissipation Section and Figure 6 ....................................................................................... 6 Added Table 4; Renumbered Tables Sequentially ......................... 6 Deleted Figure 11 .............................................................................. 6 Changes to Typical Performance Characteristics Section ........... 7 Deleted Figure 12 .............................................................................. 7 Changes to Wideband, Noninverting Gain Operation Section, Wideband, Inverting Gain Operation Section, and Table 5 ...... 15 Added Table 6 .................................................................................. 16 Changes to Figure 52 ...................................................................... 16 Added Figure 53 .............................................................................. 16 Changed Layout of Driving Capacitive Loads Section .............. 17 Added Disable Feature (ADA4891-3 Only) Section and Single-Supply Operation Section .......................................... 18 Added Multiplexer Section ............................................................ 19 Updated Outline Dimensions........................................................ 21 Changes to Ordering Guide ........................................................... 23 6/10--Rev. 0 to Rev. A Changes to Figure 26 ........................................................................ 9 Changes to Figure 33 and Figure 34 ............................................. 10 Updated Outline Dimensions........................................................ 18 Changes to Ordering Guide ........................................................... 18 2/10--Revision 0: Initial Version Rev. F | Page 3 of 24 ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 Data Sheet SPECIFICATIONS 5 V OPERATION TA = 25C, VS = 5 V, RL = 1 k to 2.5 V, unless otherwise noted. All specifications are for the ADA4891-1, ADA4891-2, ADA4891-3, and ADA4891-4, unless otherwise noted. For the ADA4891-1 and ADA4891-2, RF = 604 ; for the ADA4891-3 and ADA4891-4, RF = 453 , unless otherwise noted. Table 1. Parameter DYNAMIC PERFORMANCE -3 dB Small-Signal Bandwidth Bandwidth for 0.1 dB Gain Flatness Slew Rate, tR/tF -3 dB Large-Signal Frequency Response Settling Time to 0.1% NOISE/DISTORTION PERFORMANCE Harmonic Distortion, HD2/HD3 Input Voltage Noise Differential Gain Error (NTSC) Differential Phase Error (NTSC) All-Hostile Crosstalk DC PERFORMANCE Input Offset Voltage Test Conditions/Comments Min ADA4891-1/ADA4891-2, G = +1, VO = 0.2 V p-p ADA4891-3/ADA4891-4, G = +1, VO = 0.2 V p-p ADA4891-1/ADA4891-2, G = +2, VO = 0.2 V p-p, RL = 150 to 2.5 V ADA4891-3/ADA4891-4, G = +2, VO = 0.2 V p-p, RL = 150 to 2.5 V ADA4891-1/ADA4891-2, G = +2, VO = 2 V p-p, RL = 150 to 2.5 V, RF = 604 ADA4891-3/ADA4891-4, G = +2, VO = 2 V p-p, RL = 150 to 2.5 V, RF = 374 G = +2, VO = 2 V step, 10% to 90% G = +2, VO = 2 V p-p, RL = 150 G = +2, VO = 2 V step fC = 1 MHz, VO = 2 V p-p, G = +1 fC = 1 MHz, VO = 2 V p-p, G = -1 f = 1 MHz G = +2, RL = 150 to 2.5 V G = +2, RL = 150 to 2.5 V f = 5 MHz, G = +2, VO = 2 V p-p TMIN to TMAX W grade only, TMIN to TMAX Offset Drift Input Bias Current Open-Loop Gain W grade only, TMIN to TMAX RL = 1 k to 2.5 V W grade only, TMIN to TMAX, RL = 1 k to 2.5 V RL = 150 to 2.5 V INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Common-Mode Rejection Ratio (CMRR) OUTPUT CHARACTERISTICS Output Voltage Swing Output Current Short-Circuit Current Sourcing Sinking -50 -50 77 66 Typ Max Unit 240 220 90 MHz MHz MHz 96 MHz 25 MHz 25 MHz 170/210 40 28 V/s MHz ns -79/-93 -75/-91 9 0.05 0.25 -80 dBc dBc nV/Hz % Degrees dB 2.5 3.1 3.1 6 +2 83 71 10 16 +50 +50 mV mV mV V/C pA nA dB dB dB G pF V VCM = 0 V to 3.0 V 5 3.2 -VS - 0.3 to +VS - 0.8 88 RL = 1 k to 2.5 V RL = 150 to 2.5 V 1% THD with 1 MHz, VO = 2 V p-p 0.01 to 4.98 0.08 to 4.90 125 V V mA 205 307 mA mA Rev. F | Page 4 of 24 dB Data Sheet Parameter POWER-DOWN PINS (PD1, PD2, PD3) Threshold Voltage, VTH Bias Current Turn-On Time Turn-Off Time POWER SUPPLY Operating Range Quiescent Current per Amplifier Supply Current When Powered Down Power Supply Rejection Ratio (PSRR) Positive PSRR Negative PSRR OPERATING TEMPERATURE RANGE ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 Test Conditions/Comments ADA4891-3, ADA4891-3W only Min Typ Max 2.4 65 -22 166 49 Device enabled Device powered down Device enabled, output rises to 90% of final value Device powered down, output falls to 10% of final value 2.7 V nA A ns ns 5.5 ADA4891-3, ADA4891-3W only 4.4 0.8 +VS = 5 V to 5.25 V, -VS = 0 V +VS = 5 V, -VS = -0.25 V to 0 V 65 63 -40 Unit +125 V mA mA dB dB C 3 V OPERATION TA = 25C, VS = 3 V, RL = 1 k to 1.5 V, unless otherwise noted. All specifications are for the ADA4891-1, ADA4891-2, ADA4891-3, and ADA4891-4, unless otherwise noted. For the ADA4891-1 and ADA4891-2, RF = 604 ; for the ADA4891-3 and ADA4891-4, RF = 453 , unless otherwise noted. Table 2. Parameter DYNAMIC PERFORMANCE -3 dB Small-Signal Bandwidth Bandwidth for 0.1 dB Gain Flatness Slew Rate, tR/tF -3 dB Large-Signal Frequency Response Settling Time to 0.1% NOISE/DISTORTION PERFORMANCE Harmonic Distortion, HD2/HD3 Input Voltage Noise Differential Gain Error (NTSC) Differential Phase Error (NTSC) All-Hostile Crosstalk DC PERFORMANCE Input Offset Voltage Test Conditions/Comments Min Max Unit ADA4891-1/ADA4891-2, G = +1, VO = 0.2 V p-p ADA4891-3/ADA4891-4, G = +1, VO = 0.2 V p-p ADA4891-1/ADA4891-2, G = +2, VO = 0.2 V p-p, RL = 150 to 1.5 V ADA4891-3/ADA4891-4, G = +2, VO = 0.2 V p-p, RL = 150 to 1.5 V ADA4891-1/ADA4891-2, G = +2, VO = 2 V p-p, RL = 150 to 1.5 V, RF = 604 ADA4891-3/ADA4891-4, G = +2, VO = 2 V p-p, RL = 150 to 1.5 V, RF = 374 G = +2, VO = 2 V step, 10% to 90% G = +2, VO = 2 V p-p, RL = 150 G = +2, VO = 2 V step 190 175 75 MHz MHz MHz 80 MHz 18 MHz 18 MHz 140/230 40 30 V/s MHz ns fC = 1 MHz, VO = 2 V p-p, G = -1 f = 1 MHz G = +2, RL = 150 to 0.5 V, +VS = 2 V, -VS = -1 V G = +2, RL = 150 to 0.5 V, +VS = 2 V, -VS = -1 V f = 5 MHz, G = +2 -70/-89 9 0.23 0.77 -80 dBc nV/Hz % Degrees dB TMIN to TMAX W grade only, TMIN to TMAX Offset Drift Input Bias Current Open-Loop Gain Typ W grade only, TMIN to TMAX RL = 1 k to 1.5 V W grade only, TMIN to TMAX, RL = 1 k to 1.5 V RL = 150 to 1.5 V Rev. F | Page 5 of 24 -50 -50 72 60 2.5 3.1 3.1 6 +2 76 65 10 16 +50 +50 mV mV mV V/C pA nA dB dB dB ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 Parameter INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Test Conditions/Comments Common-Mode Rejection Ratio (CMRR) OUTPUT CHARACTERISTICS Output Voltage Swing Output Current Short-Circuit Current Sourcing Sinking POWER-DOWN PINS (PD1, PD2, PD3) Threshold Voltage, VTH Bias Current Turn-On Time Turn-Off Time POWER SUPPLY Operating Range Quiescent Current per Amplifier Supply Current When Powered Down Power Supply Rejection Ratio (PSRR) Positive PSRR Negative PSRR OPERATING TEMPERATURE RANGE Data Sheet Min Typ Max Unit VCM = 0 V to 1.5 V 5 3.2 -VS - 0.3 to +VS - 0.8 87 G pF V dB RL = 1 k to 1.5 V RL = 150 to 1.5 V 1% THD with 1 MHz, VO = 2 V p-p 0.01 to 2.98 0.07 to 2.87 37 V V mA 80 163 mA mA 1.3 48 -13 185 58 V nA A ns ns ADA4891-3, ADA4891-3W only Device enabled Device powered down Device enabled, output rises to 90% of final value Device powered down, output falls to 10% of final value 2.7 5.5 ADA4891-3, ADA4891-3W only 3.5 0.73 +VS = 3 V to 3.15 V, -VS = 0 V +VS = 3 V, -VS = -0.15 V to 0 V 76 72 -40 Rev. F | Page 6 of 24 +125 V mA mA dB dB C Data Sheet ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 ABSOLUTE MAXIMUM RATINGS To ensure proper operation, it is necessary to observe the maximum power derating curves shown in Figure 6. These curves are derived by setting TJ = 150C in Equation 1. Figure 6 shows the maximum safe power dissipation in the package vs. the ambient temperature on a JEDEC standard 4-layer board. Table 3. Rating 6V -VS - 0.5 V to +VS VS -65C to +125C -40C to +125C 300C 2.0 TJ = 150C 14-LEAD TSSOP Stresses at or above those listed under Absolute Maximum Ratings may cause permanent damage to the product. This is a stress rating only; functional operation of the product at these or any other conditions above those indicated in the operational section of this specification is not implied. Operation beyond the maximum operating conditions for extended periods may affect product reliability. 1.5 1.0 The still-air thermal properties of the package (JA), the ambient temperature (TA), and the total power dissipated in the package (PD) can be used to determine the junction temperature of the die. 8-LEAD MSOP 5-LEAD SOT-23 0.5 MAXIMUM POWER DISSIPATION The maximum power that can be safely dissipated by the ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 is limited by the associated rise in junction temperature. The maximum safe junction temperature for plastic encapsulated devices is determined by the glass transition temperature of the plastic, approximately 150C. Temporarily exceeding this limit can cause a shift in parametric performance due to a change in the stresses exerted on the die by the package. Exceeding a junction temperature of 175C for an extended period can result in device failure. 8-LEAD SOIC_N 14-LEAD SOIC_N 0 -55 -35 (1) 25 45 65 85 105 125 Figure 6. Maximum Power Dissipation vs. Ambient Temperature Table 4 lists the thermal resistance (JA) for each ADA4891-1/ ADA4891-2/ADA4891-3/ADA4891-4 package. Table 4. Package Type 5-Lead SOT-23 8-Lead SOIC_N 8-Lead MSOP 14-Lead SOIC_N 14-Lead TSSOP ESD CAUTION The power dissipated in the package (PD) is the sum of the quiescent power dissipation and the power dissipated in the package due to the load drive for all outputs. It can be calculated by PD = (VT x IS) + (VS - VOUT) x (VOUT/RL) 5 AMBIENT TEMPERATURE (C) The junction temperature can be calculated as TJ = TA + (PD x JA) -15 08054-002 MAXIMUM POWER DISSIPATION (W) Parameter Supply Voltage Input Voltage (Common Mode) Differential Input Voltage Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering, 10 sec) (2) where: VT is the total supply rail. IS is the quiescent current. VS is the positive supply rail. VOUT is the output of the amplifier. RL is the output load of the amplifier. Rev. F | Page 7 of 24 JA 146 115 133 162 108 Unit C/W C/W C/W C/W C/W ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 Data Sheet TYPICAL PERFORMANCE CHARACTERISTICS 5 3 4 NORMALIZED CLOSED-LOOP GAIN (dB) 4 1 0 G = +1 -2 -3 -4 G = +10 G = +5 -5 -6 -7 -8 VS = 5V VOUT = 200mV p-p -9 RL = 1k -10 1 0.1 0 -1 -2 -3 -4 -6 -7 1k 100 10 6 -10 0.1 VS = 2.7V 1 10 FREQUENCY (MHz) 100 6 VS = 3V VS = 2.7V CLOSED-LOOP GAIN (dB) 0 VS = 5V -3 -6 -9 10 1k 100 VS = 3V 0 VS = 5V -3 -6 -9 FREQUENCY (MHz) 5 5 4 4 +25C 3 CLOSED-LOOP GAIN (dB) +85C 2 0C +125C 1 -40C 0 -1 -2 1 FREQUENCY (MHz) 100 1k 100 1k 2 1 0 -1 -3 10 10 FREQUENCY (MHz) Figure 9. Small-Signal Frequency Response vs. Temperature, VS = 5 V, ADA4891-1/ADA4891-2 +125C +85C +25C 0C -40C 3 -2 VS = 5V G = +1 VOUT = 200mV p-p RL = 1k VS = 5V G = +1 VOUT = 200mV p-p RL = 1k -4 08054-030 -4 0.1 1 Figure 11. Small-Signal Frequency Response vs. Supply Voltage, ADA4891-3/ADA4891-4 Figure 8. Small-Signal Frequency Response vs. Supply Voltage, ADA4891-1/ADA4891-2 -3 G = +1 VOUT = 200mV p-p RL = 1k -15 0.1 08054-029 1 3 -12 G = +1 VOUT = 200mV p-p RL = 1k -15 0.1 1k Figure 10. Small-Signal Frequency Response vs. Gain, VS = 5 V, ADA4891-3/ADA4891-4 3 CLOSED-LOOP GAIN (dB) G = +10 VS = 5V VOUT = 200mV p-p RL = 1k -8 Figure 7. Small-Signal Frequency Response vs. Gain, VS = 5 V, ADA4891-1/ADA4891-2 CLOSED-LOOP GAIN (dB) G = +5 -5 -9 FREQUENCY (MHz) -12 G = +1 1 08054-077 G = -1 OR +2 G = -1 OR +2 2 0.1 1 10 FREQUENCY (MHz) 100 1k 08054-078 -1 3 08054-076 2 08054-028 NORMALIZED CLOSED-LOOP GAIN (dB) Unless otherwise noted, all plots are characterized for the ADA4891-1, ADA4891-2, ADA4891-3, and ADA4891-4. For the ADA4891-1 and ADA4891-2, the typical RF value is 604 . For the ADA4891-3 and ADA4891-4, the typical RF value is 453 . Figure 12. Small-Signal Frequency Response vs. Temperature, VS = 5 V, ADA4891-3/ADA4891-4 Rev. F | Page 8 of 24 Data Sheet ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 7 +25C 6 0C CLOSED-LOOP GAIN (dB) 3 2 1 0 -40C -1 -2 -3 -6 0.1 1 0 -1 -2 -3 -5 10 1 100 1k -6 0.1 VS = 3V G = +1 VOUT = 200mV p-p RL = 1k 100 1k Figure 16. Small-Signal Frequency Response vs. Temperature, VS = 3 V, ADA4891-3/ADA4891-4 0.1 NORMALIZED CLOSED-LOOP GAIN (dB) 0.1 0 VS = 3V VOUT = 2V p-p -0.1 VS = 5V VOUT = 1.4V p-p -0.2 VS = 5V VOUT = 2V p-p -0.3 G = +2 RF = 604 RL = 150 08054-019 VS = 3V VOUT = 1.4V p-p -0.5 0.1 1 100 10 0 VS = 5V VOUT = 1.4V p-p -0.1 -0.2 VS = 3V VOUT = 2V p-p -0.3 VS = 5V VOUT = 2V p-p -0.4 G = +2 RF = 374 RL = 150 -0.5 0.1 VS = 3V VOUT = 1.4V p-p 1 FREQUENCY (MHz) 10 FREQUENCY (MHz) 100 Figure 14. 0.1 dB Gain Flatness vs. Supply Voltage, G = +2, ADA4891-1/ADA4891-2 Figure 17. 0.1 dB Gain Flatness vs. Supply Voltage, G = +2, ADA4891-3/ADA4891-4 1 1 -1 G = +2 VOUT = 2V p-p -2 -3 NORMALIZED CLOSED-LOOP GAIN (dB) 0 G = +1 VOUT = 1V p-p G = -1 VOUT = 2V p-p -4 G = +5 VOUT = 2V p-p -5 -6 -7 -8 -9 VS = 5V RL = 150 -10 0.1 1 10 100 1k FREQUENCY (MHz) 0 Figure 15. Large-Signal Frequency Response vs. Gain, VS = 5 V, ADA4891-1/ADA4891-2 G = -1 VOUT = 2V p-p -1 -2 G = +5 VOUT = 2V p-p -3 G = +1 VOUT = 1V p-p -4 -5 -6 -7 -8 -9 -10 0.1 08054-036 NORMALIZED CLOSED-LOOP GAIN (dB) 10 1 FREQUENCY (MHz) Figure 13. Small-Signal Frequency Response vs. Temperature, VS = 3 V, ADA4891-1/ADA4891-2 NORMALIZED CLOSED-LOOP GAIN (dB) 2 -4 FREQUENCY (MHz) -0.4 3 VS = 5V RL = 150 G = +2 VOUT = 2V p-p 1 10 FREQUENCY (MHz) 100 1k Figure 18. Large-Signal Frequency Response vs. Gain, VS = 5 V, ADA4891-3/ADA4891-4 Rev. F | Page 9 of 24 08054-080 -5 VS = 3V G = +1 VOUT = 200mV p-p RL = 1k 4 -40C 08054-081 -4 08054-031 CLOSED-LOOP GAIN (dB) 5 +125C 4 +85C +125C +25C 0C 6 +85C 5 08054-079 7 ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 Data Sheet 1 G = -1 VOUT = 2V p-p -2 G = +2 VOUT = 2V p-p -3 G = +1 VOUT = 1V p-p -4 -5 G = +5 VOUT = 2V p-p -6 -7 -8 VS = 3V RL = 150 -9 -10 0.1 1 10 FREQUENCY (MHz) 100 1k G = -1 VOUT = 2V p-p -1 G = +2 VOUT = 2V p-p -2 G = +1 VOUT = 1V p-p -3 -4 G = +5 VOUT = 2V p-p -5 -6 -7 -8 VS = 3V RL = 150 -9 -10 0.1 1 10 FREQUENCY (MHz) Figure 22. Large-Signal Frequency Response vs. Gain, VS = 3 V, ADA4891-3/ADA4891-4 -40 -30 VS = 5V RL = 1k VOUT = 2V p-p G = +2 SECOND HARMONIC VS = 3V RL = 1k VOUT = 2V p-p -40 G = +1 THIRD HARMONIC -70 DISTORTION (dBc) -60 G = +1 SECOND HARMONIC -80 -90 -100 -110 G = +2 SECOND HARMONIC -50 G = +1 SECOND HARMONIC -60 +VS = +1.9V -70 OUT G = +2 THIRD HARMONIC -80 -120 0.1 1 10 FREQUENCY (MHz) IN 50 G = +2 THIRD HARMONIC G = +1 THIRD HARMONIC 1k -VS = -1.1V G = +1 CONFIGURATION -90 0.1 08054-038 1 10 FREQUENCY (MHz) Figure 20. Harmonic Distortion (HD2, HD3) vs. Frequency, VS = 5 V Figure 23. Harmonic Distortion (HD2, HD3) vs. Frequency, VS = 3 V -40 -40 G = +1 SECOND HARMONIC VS = 5V RL = 1k fC = 1MHz -50 G = +1 CONFIGURATION +VS = +1.9V -50 OUT -60 IN 50 -60 -70 DISTORTION (dBc) G = -1 SECOND HARMONIC -80 -90 -100 G = +1 THIRD HARMONIC G = -1 THIRD HARMONIC -70 1k -VS = -1.1V -80 -90 G = -1 SECOND HARMONIC G = -1 THIRD HARMONIC -100 -110 -110 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 OUTPUT VOLTAGE (V p-p) 4.0 4.5 5.0 Figure 21. Harmonic Distortion (HD2, HD3) vs. Output Voltage, VS = 5 V G = +1 THIRD HARMONIC VS = 3V fC = 1MHz -120 08054-040 -120 G = +1 SECOND HARMONIC 0 0.5 1.0 1.5 2.0 OUTPUT VOLTAGE (V p-p) 2.5 3.0 08054-041 DISTORTION (dBc) 1k Figure 19. Large-Signal Frequency Response vs. Gain, VS = 3 V, ADA4891-1/ADA4891-2 -50 DISTORTION (dBc) 100 08054-039 -1 0 08054-082 NORMALIZED CLOSED-LOOP GAIN (dB) 0 08054-037 NORMALIZED CLOSED-LOOP GAIN (dB) 1 Figure 24. Harmonic Distortion (HD2, HD3) vs. Output Voltage, VS = 3 V Rev. F | Page 10 of 24 Data Sheet G = +2 RL = 150 fC = 1MHz DISTORTION (dBc) -50 1k VS = 3V SECOND HARMONIC VS = 3V THIRD HARMONIC VOLTAGE NOISE (nV/ Hz) -40 ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 -60 -70 VS = 5V SECOND HARMONIC -80 VS = 5V THIRD HARMONIC 100 10 -90 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 OUTPUT VOLTAGE (V p-p) 100 0.06 -18 -36 50 -72 PHASE 40 -90 30 -108 20 -126 10 -144 0 -162 -10 0.001 0.01 0.1 10 1 100 -180 1k FREQUENCY (MHz) 0.04 0.02 0 -0.02 -0.04 -0.06 08054-043 -54 PHASE (Degrees) GAIN 60 NORMALIZED CLOSED-LOOP GAIN (dB) 4 1 0 CL = 0pF -1 -3 VS = 5V G = +2 RL = 150 VOUT = 200mV p-p -4 0.1 1 10 FREQUENCY (MHz) 100 1k -0.2 -0.3 9TH 10TH 6TH 7TH VS = 5V, G = +2 RL = 150 1ST 2ND 5 CL = 47pF 4 CL = 22pF 3 CL = 10pF 2 1 0 CL = 0pF -1 -2 -3 VS = 5V G = +2 RL = 150 VOUT = 200mV p-p -4 0.1 08054-044 -2 3RD 4TH 5TH 6TH 7TH 8TH MODULATING RAMP LEVEL (IRE) 5TH Figure 29. Differential Gain and Phase Errors CL = 47pF CL = 10pF 9TH 10TH 4TH 0 6 2 8TH 3RD -0.1 7 CL = 22pF 2ND 0.1 6 3 1ST 0.2 7 5 VS = 5V, G = +2 RL = 150 0.3 Figure 26. Open-Loop Gain and Phase vs. Frequency NORMALIZED CLOSED-LOOP GAIN (dB) OPEN-LOOP GAIN (dB) 70 0 DIFFERENTIAL GAIN ERROR (%) 80 10M Figure 28. Input Voltage Noise vs. Frequency DIFFERENTIAL PHASE ERROR (Degrees) VS = 5V RL = 1k 1M 100k FREQUENCY (Hz) Figure 25. Harmonic Distortion (HD2, HD3) vs. Output Voltage, G = +2 90 10k 1k 08054-045 1.0 08054-060 0.5 VS = 5V G = +1 Figure 27. Small-Signal Frequency Response vs. CL, ADA4891-1/ADA4891-2 1 10 FREQUENCY (MHz) 100 Figure 30. Small-Signal Frequency Response vs. CL, ADA4891-3/ADA4891-4 Rev. F | Page 11 of 24 1k 08054-083 0 1 10 08054-042 -100 ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 100 Data Sheet 100k VS = 5V G = +1 10k OUTPUT IMPEDANCE () OUTPUT IMPEDANCE () 10 1 0.1 1k 100 10 0.1 1 10 100 FREQUENCY (MHz) 1 0.01 08054-046 0.01 0.01 1 10 100 FREQUENCY (MHz) Figure 31. Closed-Loop Output Impedance vs. Frequency, Device Enabled VS = 3V 0.1 08054-089 VS = 5V G = +1 Figure 34. Closed-Loop Output Impedance vs. Frequency, Device Disabled (ADA4891-3 Only) 1.5 G = +1 VOUT = 200mV p-p RL = 1k G = +2 VOUT = 2V p-p VS = 5V RL = 1k OUTPUT VOLTAGE (V) 0 -100 50mV/DIV 10ns/DIV 0.5 -0.5 -1.5 10 20 30 40 50 60 TIME (ns) 70 80 90 Figure 35. Large-Signal Step Response, G = +2 VS = 3V G = +1 VOUT = 1V p-p RL = 1k OUTPUT VOLTAGE (V) 0.5 RL = 150 0 -1 RL = 150 0 0.5V/DIV 10ns/DIV 0.5V/DIV 10ns/DIV Figure 36. Large-Signal Step Response, VS = 3 V, G = +1 Figure 33. Large-Signal Step Response, VS = 5 V, G = +1 Rev. F | Page 12 of 24 08054-050 -0.5 08054-049 OUTPUT VOLTAGE (V) VS = 3V RL = 1k -1.0 VS = 5V G = +1 VOUT = 2V p-p 1 VS = 3V RL = 150 0 Figure 32. Small-Signal Step Response, G = +1 RL = 1k VS = 5V RL = 150 08054-047 VS = 5V 08054-048 OUTPUT VOLTAGE (mV) 1.0 100 Data Sheet ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 200 0.30 VS = 5V G = +2 RL = 150 VOUT = 2V p-p 0.20 190 FALLING EDGE SLEW RATE (V/s) 0.10 0 -0.10 -0.20 180 170 160 RISING EDGE 0 25 30 35 40 45 TIME (ns) 140 1.0 1.5 3.5 4.5 4.0 5.0 1 VS = 2.5V G = +1 RL = 1k VS = 2.5V G = +1 RL = 1k OUTPUT INPUT AMPLITUDE (V) 0 1 -1 OUTPUT -2 1V/DIV 5ns/DIV -1 08054-071 0 1V/DIV Figure 38. Input Overdrive Recovery from Positive Rail 3 Figure 41. Input Overdrive Recovery from Negative Rail 3 VS = 2.5V G = -2 RL = 1k OUTPUT 2 INPUT 2 AMPLITUDE (V) 1 INPUT 0 -1 -2 -3 08054-070 5ns/DIV VS = 2.5V G = -2 RL = 1k 1 0 -1 -2 1V/DIV 5ns/DIV -3 08054-063 INPUT AMPLITUDE (V) 3.0 Figure 40. Slew Rate vs. Output Step 3 AMPLITUDE (V) 2.5 OUTPUT STEP (V) Figure 37. Short-Term Settling Time to 0.1% 2 2.0 08054-051 -0.30 08054-061 150 OUTPUT 1V/DIV 5ns/DIV -3 Figure 39. Output Overdrive Recovery from Positive Rail Figure 42. Output Overdrive Recovery from Negative Rail Rev. F | Page 13 of 24 08054-052 SETTLING (%) VS = 5V G = +2 RL = 150 ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 Data Sheet -10 0 VS = 5V VS = 5V G = +2 RL = 150 -10 -20 -20 -30 ISOLATION (dB) CMRR (dB) -30 -40 -50 -60 TSSOP -40 -50 -60 SOIC -70 -70 -80 -80 0.1 1 10 100 FREQUENCY (MHz) -100 0.1 08054-090 -90 0.01 1.0 Vs = 5V G = +1 OUTPUT SATURATION VOLTAGE (V) -20 -30 PSRR (dB) 100 1k VS = 5V G = -2 0.9 -40 +PSRR -50 -60 10 FREQUENCY (MHz) Figure 46. Forward Isolation vs. Frequency (ADA4891-3 Only) Figure 43. CMRR vs. Frequency -10 1 08054-084 -90 -PSRR -70 0.8 0.7 VOH, +125C VOH, +25C VOH, -40C VOL, +125C VOL, +25C VOL, -40C 0.6 0.5 0.4 0.3 0.2 0.1 1 10 100 FREQUENCY (MHz) 0 Figure 44. PSRR vs. Frequency 0 40 50 60 70 80 90 100 6.0 Vs = 5V G = +2 RL = 1 k VOUT = 2V p-p VS = 5V -30 -40 -50 -60 -70 -80 5.5 5.0 4.5 4.0 3.5 -100 0.1 1 10 100 1k FREQUENCY (MHz) Figure 45. All-Hostile Crosstalk (Output-to-Output) vs. Frequency 3.0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C) Figure 48. Supply Current per Amplifier vs. Temperature Rev. F | Page 14 of 24 08054-057 -90 08054-072 CROSSTALK (dB) 30 Figure 47. Output Saturation Voltage vs. Load Current and Temperature QUIESCENT SUPPLY CURRENT (mA) -20 20 ILOAD (mA) 0 -10 10 08054-056 0.1 08054-054 -80 0.01 Data Sheet ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8 SUPPLY VOLTAGE (V) 08054-058 QUIESCENT SUPPLY CURRENT (mA) 4.4 Figure 49. Supply Current per Amplifier vs. Supply Voltage Rev. F | Page 15 of 24 ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 Data Sheet APPLICATIONS INFORMATION WIDEBAND, INVERTING GAIN OPERATION +VS Understanding the subtleties of the ADA4891-1/ADA4891-2/ ADA4891-3/ADA4891-4 family of amplifiers provides insight into how to extract the peak performance from the device. The following sections describe the effect of gain, component values, and parasitics on the performance of the ADA4891-1/ADA4891-2/ ADA4891-3/ADA4891-4. The wideband, noninverting gain configuration of the ADA4891-1/ADA4891-2/ADA4891-3/ ADA4891-4 is shown in Figure 50; the wideband, inverting gain configuration of the ADA4891-1/ADA4891-2/ADA4891-3/ ADA4891-4 is shown in Figure 51. 0.1F VO ADA4891 50 SOURCE 0.1F 10F Figure 51. Inverting Gain Configuration Figure 51 shows the inverting gain configuration. For the inverting gain configuration, set the parallel combination of RT and RG to match the input source impedance. 10F Note that a bias current cancellation resistor is not required in the noninverting input of the amplifier because the input bias current of the ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 is very low (less than 2 pA). Therefore, the dc errors caused by the bias current are negligible. VO ADA4891 RL RF RG 10F 08054-023 0.1F RF -VS 50 SOURCE RT RG RT +VS VI RL VI WIDEBAND, NONINVERTING GAIN OPERATION 0.1F 10F 08054-024 USING THE ADA4891-1/ADA4891-2/ADA4891-3/ ADA4891-4 -VS Figure 50. Noninverting Gain Configuration In Figure 50, RF and RG denote the feedback and gain resistors, respectively. Together, RF and RG determine the noise gain of the amplifier. The value of RF defines the 0.1 dB bandwidth (for more information, see the Effect of RF on 0.1 dB Gain Flatness section). Typical RF values range from 549 to 698 for the ADA4891-1/ADA4891-2. Typical RF values range from 301 to 453 for the ADA4891-3/ADA4891-4. In a controlled impedance signal path, RT is used as the input termination resistor designed to match the input source impedance. Note that RT is not required for normal operation. RT is generally set to match the input source impedance. For both noninverting and inverting gain configurations, it is often useful to increase the RF value to decrease the load on the output. Increasing the RF value improves harmonic distortion at the expense of reducing the 0.1 dB bandwidth of the amplifier. This effect is discussed further in the Effect of RF on 0.1 dB Gain Flatness section. RECOMMENDED VALUES Table 5 and Table 6 provide a quick reference for various configurations and show the effect of gain on the -3 dB small-signal bandwidth, slew rate, and peaking of the ADA4891-1/ADA4891-2/ ADA4891-3/ADA4891-4. Note that as the gain increases, the small-signal bandwidth decreases, as is expected from the gain bandwidth product relationship. In addition, the phase margin improves with higher gains, and the amplifier becomes more stable. As a result, the peaking in the frequency response is reduced (see Figure 7 and Figure 10). Table 5. Recommended Component Values and Effect of Gain on ADA4891-1/ADA4891-2 Performance (RL = 1 k) Gain -1 +1 +2 +5 +10 Feedback Network Values RF () RG () 604 604 0 Open 604 604 604 151 604 67.1 -3 dB Small-Signal Bandwidth (MHz) VOUT = 200 mV p-p 118 240 120 32.5 12.7 Rev. F | Page 16 of 24 tR 188 154 170 149 71 Slew Rate (V/s) tF 192 263 210 154 72 Peaking (dB) 1.3 2.6 1.4 0 0 Data Sheet ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 Table 6. Recommended Component Values and Effect of Gain on ADA4891-3/ADA4891-4 Performance (RL = 1 k) -3 dB Small-Signal Bandwidth (MHz) VOUT = 200 mV p-p 97 220 97 31 13 EFFECT OF RF ON 0.1 dB GAIN FLATNESS Figure 52 and Figure 53 show the effect of using various values for Feedback Resistor RF on the 0.1 dB gain flatness of the devices. Figure 52 shows the effect for the ADA4891-1/ADA4891-2. Figure 53 show the effect for the ADA4891-3/ADA4891-4. Note that a larger RF value causes more peaking because the additional pole formed by RF and the input stray capacitance shifts down in frequency and interacts significantly with the internal poles of the amplifier. 0.2 -0.1 -0.2 -0.4 RG = RF = 453 0.2 RG = RF = 402 RG = RF = 357 0.1 0 RG = RF = 301 -0.1 -0.2 -0.3 -0.4 -0.5 VS = 5V G = +2 VOUT = 2V p-p RL = 150 0.1 1 10 100 FREQUENCY (MHz) Figure 53. 0.1 dB Gain Flatness, Noninverting Gain Configuration, ADA4891-3/ADA4891-4 To obtain the desired 0.1 dB bandwidth, adjust the feedback resistor, RF, as shown in Figure 52 and Figure 53. If RF cannot be adjusted, a small capacitor can be placed in parallel with RF to reduce peaking. The feedback capacitor, CF, forms a zero with the feedback resistor, which cancels out the pole formed by the input stray capacitance and the gain and feedback resistors. For a first pass in determining the CF value, use the following equation: where: RG is the gain resistor. CS is the input stray capacitance. RF is the feedback resistor. CF is the feedback capacitor. RG = RF = 549 -0.3 Peaking (dB) 0.9 4.1 0.9 0 0 RG x CS = RF x CF 0 VS = 5V G = +2 VOUT = 2V p-p RL = 150 0.1 1 10 100 FREQUENCY (MHz) Figure 52. 0.1 dB Gain Flatness, Noninverting Gain Configuration, ADA4891-1/ADA4891-2 08054-022 NORMALIZED CLOSED-LOOP GAIN (dB) RG = RF = 649 RG = RF = 604 NORMALIZED CLOSED-LOOP GAIN (dB) The PCB layout configuration and bond pads of the chip often contribute to stray capacitance. The stray capacitance at the inverting input forms a pole with the feedback and gain resistors. This additional pole adds phase shift and reduces phase margin in the closed-loop phase response, causing instability in the amplifier and peaking in the frequency response. 0.1 Slew Rate (V/s) tF 194 262 223 120 67 0.3 Gain flatness is an important specification in video applications. It represents the maximum allowable deviation in the signal amplitude within the pass band. Tests have revealed that the human eye is unable to distinguish brightness variations of less than 1%, which translates into a 0.1 dB signal drop within the pass band or, put simply, 0.1 dB gain flatness. RG = RF = 698 tR 186 151 181 112 68 08054-085 Feedback Network Values RF () RG () 453 453 0 Open 453 453 453 90.6 453 45.3 Gain -1 +1 +2 +5 +10 Using this equation, the original closed-loop frequency response of the amplifier is restored, as if there is no stray input capacitance. Most often, however, the value of CF is determined empirically. Figure 54 shows the effect of using various values for the feedback capacitor to reduce peaking. In this case, the ADA4891-1/ ADA4891-2 are used for demonstration purposes and RF = RG = 604 . The input stray capacitance, together with the board parasitics, is approximately 2 pF. Rev. F | Page 17 of 24 ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 These four methods minimize the output capacitive loading effect. Reducing the output resistive load. This pushes the pole further away and, therefore, improves the phase margin. Increasing the phase margin with higher noise gains. As the closed-loop gain is increased, the larger phase margin allows for large capacitive loads with less peaking. Adding a parallel capacitor (CF) with RF, from -IN to the output. This adds a zero in the closed-loop frequency response, which tends to cancel out the pole formed by the capacitive load and the output impedance of the amplifier. See the Effect of RF on 0.1 DB Gain Flatness section for more information. Placing a small value resistor (RS) in series with the output to isolate the load capacitor from the output stage of the amplifier. CF = 1pF 0 -0.2 CF = 3.3pF -0.1 VS = 5V G = +2 RF = 604 RL = 150 VOUT = 2V p-p -0.3 0.1 1 10 100 FREQUENCY (MHz) Figure 54. 0.1 dB Gain Flatness vs. CF, VS = 5 V, ADA4891-1/ADA4891-2 DRIVING CAPACITIVE LOADS A highly capacitive load reacts with the output impedance of the amplifiers, causing a loss of phase margin and subsequent peaking or even oscillation. The ADA4891-1/ADA4891-2 are used to demonstrate this effect (see Figure 55 and Figure 56). 8 Figure 57 shows the effect of using a snub resistor (RS) on reducing the peaking in the worst-case frequency response (gain of +1). Using RS = 100 reduces the peaking by 3 dB, with the trade-off that the closed-loop gain is reduced by 0.9 dB due to attenuation at the output. RS can be adjusted from 0 to 100 to maintain an acceptable level of peaking and closed-loop gain, as shown in Figure 57. 6 8 2 4 MAGNITUDE (dB) 0 -2 -4 -6 -8 VS = 5V VOUT = 200mV p-p G = +1 RL = 1k CL = 6.8pF 6 VS = 5V VOUT = 200mV p-p G = +1 RL = 1k CL = 6.8pF -10 0.1 1 2 10 100 FREQUENCY (MHz) RS = 0 0 RS = 100 -2 -4 -6 -8 08054-032 MAGNITUDE (dB) 4 VIN 200mV STEP RS CL 50 -10 0.1 Figure 55. Closed-Loop Frequency Response, CL = 6.8 pF, ADA4891-1/ADA4891-2 OUT RL 1 10 100 FREQUENCY (MHz) 08054-033 CF = 0pF 0.1 08054-025 NORMALIZED CLOSED-LOOP GAIN (dB) 0.2 Data Sheet Figure 57. Closed-Loop Frequency Response with Snub Resistor, CL = 6.8 pF Figure 58 shows that the transient response is also much improved by the snub resistor (RS = 100 ) compared to that of Figure 56. VS = 5V G = +1 RL = 1k CL = 6.8pF RS = 100 0 -100 50mV/DIV 50ns/DIV Figure 56. 200 mV Step Response, CL = 6.8 pF, ADA4891-1/ADA4891-2 100 0 -100 50mV/DIV 50ns/DIV Figure 58. 200 mV Step Response, CL = 6.8 pF, RS = 100 Rev. F | Page 18 of 24 08054-035 OUTPUT VOLTAGE (mV) 100 08054-034 OUTPUT VOLTAGE (mV) VS = 5V G = +1 RL = 1k CL = 6.8pF Data Sheet ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 TERMINATING UNUSED AMPLIFIERS SINGLE-SUPPLY OPERATION Terminating unused amplifiers in a multiamplifier package is an important step in ensuring proper operation of the functional amplifier. Unterminated amplifiers can oscillate and draw excessive power. The recommended procedure for terminating unused amplifiers is to connect any unused amplifiers in a unity-gain configuration and to connect the noninverting input to midsupply voltage. With symmetrical bipolar power supplies, this means connecting the noninverting input to ground, as shown in Figure 59. The ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 can also be operated from a single power supply. Figure 61 shows the ADA4891-3 configured as a single 5 V supply video driver. +VS ADA4891 The large-signal frequency response obtained with singlesupply operation is identical to the bipolar supply operation (Figure 18 shows the large-signal frequency response). 08054-064 -VS The input signal is ac-coupled into the amplifier via Capacitor 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 (RG) and enables the ADA4891-3 at dc to provide unity gain to the input midsupply voltage, thereby establishing the output voltage at midsupply. Capacitor C6 is the output coupling capacitor. Figure 59. Terminating Unused Amplifier with Symmetrical Bipolar Power Supplies In single power supply applications, a synthetic midsupply source must be created. This can be accomplished with a simple resistive voltage divider. Figure 60 shows the proper connection for terminating an unused amplifier in a single-supply configuration. +VS 2.5k Four pairs of low frequency poles are formed by R2/2 and C2, R3 and C1, RG and C5, and RL and C6. With this configuration, the -3 dB cutoff frequency at low frequency is 12 Hz. The values of C1, C2, C5, and C6 can be adjusted to change the low frequency -3 dB cutoff point to suit individual design needs. For more information about single-supply operation of op amps, see the Analog Dialogue article "Avoiding Op Amp Instability Problems in Single-Supply Applications" (Volume 35, Number 2) at www.analog.com. +5V +5V Figure 60. Terminating Unused Amplifier with Single Power Supply The ADA4891-3 includes a power-down feature that can be used to save power when an amplifier is not in use. When an amplifier is powered down, its output goes to a high impedance state. The output impedance decreases as frequency increases; this effect can be observed in Figure 34. With the power-down function, a forward isolation of -40 dB can be achieved at 50 MHz. Figure 46 shows the forward isolation vs. frequency data. The power-down feature is asserted by pulling the PD1, PD2, or PD3 pin low. R4 50k C4 0.01F C6 22F VIN Table 7 summarizes the operation of the power-down feature. Table 7. Disable Function >VTH or floating <VTH C3 10F R3 100k DISABLE FEATURE (ADA4891-3 ONLY) Power-Down Pin Connection (PDx) R2 50k C2 1F Amplifier Status Enabled Disabled Rev. F | Page 19 of 24 R1 50 C1 22F VOUT RL 150 RG 453 C5 22F RF 453 ADA4891-3 -VS Figure 61. Single-Supply Video Driver Schematic 08054-086 ADA4891 08054-065 2.5k ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 Data Sheet VIDEO RECONSTRUCTION FILTER MULTIPLEXER A common application for active filters is at the output of video digital-to-analog converters (DACs)/encoders. The filter, or more appropriately, the video reconstruction filter, is used at the output of a video DAC/encoder to eliminate the multiple images that are created during the sampling process within the DAC. For portable video applications, the ADA4891-1/ADA4891-2/ ADA4891-3/ADA4891-4 is an ideal choice due to its lower power requirements and high performance. The ADA4891-3 has a disable pin used to power down the amplifier to save power or to create a mux circuit. If two or more ADA4891-3 outputs are connected together and only one output is enabled, then only the signal of the enabled amplifier appears at the output. This configuration is used to select from various input signal sources. Additionally, the same input signal is applied to different gain stages, or differently tuned filters, to make a gain-step amplifier or a selectable frequency amplifier. For active filters, a good rule of thumb is that the -3 dB bandwidth of the amplifiers be at least 10 times higher than the corner frequency of the filter. This ensures that no initial roll-off is introduced by the amplifier and that the pass band is flat until the cutoff frequency. Figure 64 shows a schematic of two ADA4891-3 devices used to create a mux that selects between two inputs. One input is a 1 V p-p, 3 MHz sine wave; the other input is a 2 V p-p, 1 MHz sine wave. An example of a 15 MHz, 3-pole, Sallen-Key, low-pass video reconstruction filter is shown in Figure 62. This circuit features a gain of +2, a 0.1 dB bandwidth of 7.3 MHz, and over 17 dB attenuation at 29.7 MHz (see Figure 63). The filter has three poles: two poles are active, with a third passive pole (R6 and C4) placed at the output. C3 improves the filter roll-off. R6, R7, and R8 make up the video load of 150 . Components R6, C4, R7, R8, and the input termination of the network analyzer form a 6 dB attenuator; therefore, the reference level is roughly 0 dB, as shown in Figure 63. +2.5V 49.9 VIN +5V R4 1k 49.9 453 VOUT 49.9 +2.5V 0.1F 10F 0.1F 10F 49.9 49.9 ADA4891-3 R7 68.1 C4 1nF 10F 453 VOUT C1 51pF R1 0.1F ADA4891-3 -2.5V 2V p-p 1MHz R6 6.8 10F 1V p-p 3MHz C2 51pF R3 R2 47 125 0.1F R8 75 -2.5V 453 08054-087 453 HCO4 C3 15pF SELECT 08054-062 R5 1k Figure 62. 15 MHz Video Reconstruction Filter Schematic Figure 64. Two-to-One Multiplexer Using Two ADA4891-3 Devices The select signal and the output waveforms for this circuit are shown in Figure 65. 0 -3 1V/DIV 1s/DIV 5V/DIV 1s/DIV -6 OUTPUT -15 -18 -21 -24 SELECT -27 -30 -36 -39 0.03 0.1 1 10 100 FREQUENCY (MHz) Figure 63. Video Reconstruction Filter Frequency Performance Rev. F | Page 20 of 24 Figure 65. ADA4891-3 Mux Output 08054-088 -33 08054-059 MAGNITUDE (dB) -9 -12 Data Sheet ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 LAYOUT, GROUNDING, AND BYPASSING POWER SUPPLY BYPASSING Power supply pins are additional op amp inputs, and care must be taken so that a noise-free, stable dc voltage is applied. The purpose of bypass capacitors is to create a low impedance path from the supply to ground over a range of frequencies, thereby shunting or filtering the majority of the noise to ground. Bypassing is also critical for stability, frequency response, distortion, and PSRR performance. If traces are used between components and the package, chip capacitors of 0.1 F (X7R or NPO) are critical and should be placed as close as possible to the amplifier package. The 0508 case size for such a capacitor is recommended because it offers low series inductance and excellent high frequency performance. Larger chip capacitors, such as 0.1 F capacitors, can be shared among a few closely spaced active components in the same signal path. A 10 F tantalum capacitor is less critical for high frequency bypassing, but it provides additional bypassing for lower frequencies. GROUNDING When possible, ground and power planes should be used. Ground and power planes reduce the resistance and inductance of the power supply feeds and ground returns. If multiple planes are used, they should be stitched together with multiple vias. The returns for the input, output terminations, bypass capacitors, and RG should all be kept as close to the ADA4891-1/ADA4891-2/ ADA4891-3/ADA4891-4 as possible. Ground vias should be placed at the side or at the very end of the component mounting pads to provide a solid ground return. The output load ground and the bypass capacitor grounds should be returned to a common point on the ground plane to minimize parasitic inductance and to help improve distortion performance. be kept at a distance of at least 0.05 mm from the input pins on all layers of the board. INPUT-TO-OUTPUT COUPLING To minimize capacitive coupling between the inputs and outputs and to avoid any positive feedback, the input and output signal traces should not be parallel. In addition, the input traces should not be close to each other. A minimum of 7 mils between the two inputs is recommended. LEAKAGE CURRENTS In extremely low input bias current amplifier applications, stray leakage current paths must be kept to a minimum. Any voltage differential between the amplifier inputs and nearby traces sets up a leakage path through the PCB. Consider a 1 V signal and 100 G to ground present at the input of the amplifier. The resultant leakage current is 10 pA; this is 5x the typical input bias current of the amplifier. Poor PCB layout, contamination, and the board material can create large leakage currents. Common contaminants on boards are skin oils, moisture, solder flux, and cleaning agents. Therefore, it is imperative that the board be thoroughly cleaned and that the board surface be free of contaminants to take full advantage of the low input bias currents of the ADA4891-1/ADA4891-2/ ADA4891-3/ADA4891-4. To significantly reduce leakage paths, a guard ring/shield should be used around the inputs. The guard ring circles the input pins and is driven to the same potential as the input signal, thereby reducing the potential difference between pins. For the guard ring to be completely effective, it must be driven by a relatively low impedance source and should completely surround the input leads on all sides, above and below, using a multilayer board (see Figure 66). GUARD RING Parasitic capacitance can cause peaking and instability and, therefore, should be minimized to ensure stable operation. GUARD RING NONINVERTING INVERTING Figure 66. Guard Ring Configurations The 5-lead SOT-23 package for the ADA4891-1 presents a challenge in keeping the leakage paths to a minimum. The pin spacing is very tight, so extra care must be used when constructing the guard ring (see Figure 67 for the recommended guard ring construction). In addition, the ground and power planes under the pins of the ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 should be cleared of copper to prevent parasitic capacitance between the input and output pins to ground. This is because a single mounting pad on a SOIC footprint can add as much as 0.2 pF of capacitance to ground if the ground or power plane is not cleared under the ADA4891-1/ADA4891-2/ADA4891-3/ ADA4891-4 pins. In fact, the ground and power planes should Rev. F | Page 21 of 24 OUT ADA4891-1 +VS OUT ADA4891-1 +VS -VS -VS +IN -IN INVERTING +IN -IN NONINVERTING Figure 67. Guard Ring Layout, 5-Lead SOT-23 08054-068 High speed amplifiers are sensitive to parasitic capacitance between the inputs and ground. A few picofarads of capacitance reduce the input impedance at high frequencies, in turn increasing the gain of the amplifier and causing peaking of the frequency response or even oscillations, if severe enough. It is recommended that the external passive components that are connected to the input pins be placed as close as possible to the inputs to avoid parasitic capacitance. 08054-067 INPUT AND OUTPUT CAPACITANCE ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 Data Sheet OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 1 5 4 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 6.20 (0.2441) 5.80 (0.2284) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) 0.31 (0.0122) COPLANARITY 0.10 SEATING PLANE 0.50 (0.0196) 0.25 (0.0099) 45 8 0 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) COMPLIANT TO JEDEC STANDARDS MS-012-AA 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. 012407-A 8 4.00 (0.1574) 3.80 (0.1497) Figure 68. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) 3.00 2.90 2.80 1.70 1.60 1.50 5 1 4 2 3.00 2.80 2.60 3 0.95 BSC 1.90 BSC 1.45 MAX 0.95 MIN 0.15 MAX 0.05 MIN 0.50 MAX 0.35 MIN 0.20 MAX 0.08 MIN SEATING PLANE 10 5 0 0.60 BSC COMPLIANT TO JEDEC STANDARDS MO-178-AA Figure 69. 5-Lead Small Outline Transistor Package [SOT-23] (RJ-5) Dimensions shown in millimeters Rev. F | Page 22 of 24 0.55 0.45 0.35 11-01-2010-A 1.30 1.15 0.90 Data Sheet ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 3.20 3.00 2.80 8 3.20 3.00 2.80 5.15 4.90 4.65 5 1 4 PIN 1 IDENTIFIER 0.65 BSC 0.95 0.85 0.75 15 MAX 1.10 MAX 0.80 0.55 0.40 0.23 0.09 6 0 0.40 0.25 10-07-2009-B 0.15 0.05 COPLANARITY 0.10 COMPLIANT TO JEDEC STANDARDS MO-187-AA Figure 70. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters 8.75 (0.3445) 8.55 (0.3366) 4.00 (0.1575) 3.80 (0.1496) 8 14 1 7 6.20 (0.2441) 5.80 (0.2283) 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0039) COPLANARITY 0.10 0.50 (0.0197) 0.25 (0.0098) 1.75 (0.0689) 1.35 (0.0531) SEATING PLANE 0.51 (0.0201) 0.31 (0.0122) 45 8 0 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) 060606-A 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 71. 14-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-14) Dimensions shown in millimeters and (inches) 5.10 5.00 4.90 14 8 4.50 4.40 4.30 6.40 BSC 1 7 PIN 1 0.65 BSC 1.20 MAX 0.15 0.05 COPLANARITY 0.10 0.30 0.19 SEATING PLANE 0.20 0.09 8 0 0.75 0.60 0.45 COMPLIANT TO JEDEC STANDARDS MO-153-AB-1 Figure 72. 14-Lead Thin Shrink Small Outline Package [TSSOP] (RU-14) Dimensions shown in millimeters Rev. F | Page 23 of 24 061908-A 1.05 1.00 0.80 ADA4891-1/ADA4891-2/ADA4891-3/ADA4891-4 Data Sheet ORDERING GUIDE Model 1, 2 ADA4891-1ARZ ADA4891-1ARZ-RL ADA4891-1ARZ-R7 ADA4891-1ARJZ-R7 ADA4891-1ARJZ-RL ADA4891-1WARJZ-R7 ADA4891-2ARZ ADA4891-2ARZ-RL ADA4891-2ARZ-R7 ADA4891-2ARMZ ADA4891-2ARMZ-RL ADA4891-2ARMZ-R7 ADA4891-2WARMZ-R7 ADA4891-3ARUZ ADA4891-3ARUZ-R7 ADA4891-3ARUZ-RL ADA4891-3WARUZ-R7 ADA4891-3ARZ ADA4891-3ARZ-R7 ADA4891-3ARZ-RL ADA4891-4ARUZ ADA4891-4ARUZ-R7 ADA4891-4ARUZ-RL ADA4891-4WARUZ-R7 ADA4891-4ARZ ADA4891-4ARZ-R7 ADA4891-4ARZ-RL ADA4891-1AR-EBZ ADA4891-1ARJ-EBZ ADA4891-2AR-EBZ ADA4891-2ARM-EBZ ADA4891-3AR-EBZ ADA4891-3ARU-EBZ ADA4891-4AR-EBZ ADA4891-4ARU-EBZ 1 2 Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C Package Description 8-Lead SOIC_N 8-Lead SOIC_N, 13" Tape and Reel 8-Lead SOIC_N, 7" Tape and Reel 5-Lead SOT-23, 7" Tape and Reel 5-Lead SOT-23, 13" Tape and Reel 5-Lead SOT-23, 7" Tape and Reel 8-Lead SOIC_N 8-Lead SOIC_N, 13" Tape and Reel 8-Lead SOIC_N, 7" Tape and Reel 8-Lead MSOP 8-Lead MSOP, 13" Tape and Reel 8-Lead MSOP, 7" Tape and Reel 8-Lead MSOP, 7" Tape and Reel 14-Lead TSSOP 14-Lead TSSOP, 7" Tape and Reel 14-Lead TSSOP, 13" Tape and Reel 14-Lead TSSOP, 7" Tape and Reel 14-Lead SOIC_N 14-Lead SOIC_N, 7" Tape and Reel 14-Lead SOIC_N, 13" Tape and Reel 14-Lead TSSOP 14-Lead TSSOP, 7" Tape and Reel 14-Lead TSSOP, 13" Tape and Reel 14-Lead TSSOP, 7" Tape and Reel 14-Lead SOIC_N 14-Lead SOIC_N, 7" Tape and Reel 14-Lead SOIC_N, 13" Tape and Reel Evaluation Board for 8-Lead SOIC_N Evaluation Board for 5-Lead SOT-23 Evaluation Board for 8-Lead SOIC_N Evaluation Board for 8-Lead MSOP Evaluation Board for 14-Lead SOIC_N Evaluation Board for 14-Lead TSSOP Evaluation Board for 14-Lead SOIC_N Evaluation Board for 14-Lead TSSOP Package Option R-8 R-8 R-8 RJ-5 RJ-5 RJ-5 R-8 R-8 R-8 RM-8 RM-8 RM-8 RM-8 RU-14 RU-14 RU-14 RU-14 R-14 R-14 R-14 RU-14 RU-14 RU-14 RU-14 R-14 R-14 R-14 Branding H1W H1W H2S H1U H1U H1U H2T Z = RoHS Compliant Part. W = Qualified for Automotive Applications. AUTOMOTIVE PRODUCTS The ADA4891-1W, ADA4891-2W, ADA4891-3W, and ADA4891-4W models are available with controlled manufacturing to support the quality and reliability requirements of automotive applications. Note that these automotive models may have specifications that differ from the commercial models; therefore, designers should review the Specifications section of this data sheet carefully. Only the automotive grade products shown are available for use in automotive applications. Contact your local Analog Devices, Inc., account representative for specific product ordering information and to obtain the specific Automotive Reliability reports for these models. (c)2010-2015 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D08054-0-9/15(F) Rev. F | Page 24 of 24