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| a FEATURES Single AD8041 and Dual AD8042 Also Available Fully Specified at +3 V, +5 V, and 5 V Supplies Output Swings to Within 25 mV of Either Rail Input Voltage Range Extends 200 mV Below Ground No Phase Reversal with Inputs 1 V Beyond Supplies Low Power of 2.75 mA/Amplifier High Speed and Fast Settling on +5 V 150 MHz -3 dB Bandwidth (G = +1) 170 V/ s Slew Rate 40 ns Settling Time to 0.1% Good Video Specifications (RL = 150 , G = +2) Gain Flatness of 0.1 dB to 12 MHz 0.06% Differential Gain Error 0.15 Differential Phase Error Low Distortion -68 dBc Total Harmonic @ 5 MHz Outstanding Load Drive Capability Drives 30 mA 0.5 V from Supply Rails APPLICATIONS Active Filters Video Switchers Distribution Amplifiers A/D Driver Professional Cameras CCD Imaging Systems Ultrasound Equipment (Multichannel) Quad 150 MHz Rail-to-Rail Amplifier AD8044 CONNECTION DIAGRAM 14-Lead Plastic DIP and SOIC OUT A -IN A +IN A V+ +IN B -IN B OUT B 1 2 3 4 5 6 7 14 OUT D 13 -IN D 12 +IN D AD8044 11 V- 10 +IN C 9 8 -IN C OUT C TOP VIEW The output voltage swing extends to within 25 mV of each rail, providing the maximum output dynamic range. Additionally, it features gain flatness of 0.1 dB to 12 MHz, while offering differential gain and phase error of 0.04% and 0.22 on a single +5 V supply. This makes the AD8044 useful for video electronics, such as cameras, video switchers, or any high speed portable equipment. The AD8044's low distortion and fast settling make it ideal for active filter applications. The AD8044 offers low power supply current of 13.1 mA max and can run on a single +3.3 V power supply. These features are ideally suited for portable and battery-powered applications where size and power are critical. The wide bandwidth of 150 MHz, along with 170 V/ms of slew rate on a single +5 V supply, make the AD8044 useful in many general-purpose, high speed applications where dual power supplies of up to 6 V and single supplies from +3 V to +12 V are needed. The AD8044 is available in 14-lead PDIP and SOIC. 18 15 12 VS = +5V G = +1 PRODUCT DESCRIPTION The AD8044 is a quad, low power, voltage feedback, high speed amplifier designed to operate on +3 V, +5 V, or 5 V supplies. It has true single-supply capability with an input voltage range extending 200 mV below the negative rail and within 1 V of the positive rail. VS = +5V NORMALIZED GAIN (dB) 9 6 3 0 -3 -6 -9 5V 2.5V 0V 1V 2s -12 100k 1M 10M FREQUENCY (Hz) 100M Figure 1. Output Swing: Gain = -1, RL = 2 kW Figure 2. Frequency Response: Gain = +1, VS = +5 V REV. B 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. 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: 781/326-8703 (c) 2004 Analog Devices, Inc. All rights reserved. AD8044-SPECIFICATIONS (@ T = +25 C, V = +5 V, R = 2 k A S L to 2.5 V, unless otherwise noted.) Min 80 140 AD8044A Typ 150 12 170 26 30 40 -68 16 850 0.04 0.22 -60 1.0 6 8 4.5 4.5 1.2 Max Units MHz MHz V/ms MHz ns ns dB nV//Hz fA//Hz % Degrees dB mV mV mV/C mA mA mA dB dB kW pF V dB V V V mA mA mA pF 12 13.1 +85 V mA dB C Parameter DYNAMIC PERFORMANCE -3 dB Small Signal Bandwidth, VO < 0.5 V p-p Bandwidth for 0.1 dB Flatness Slew Rate Full Power Response Settling Time to 1% Settling Time to 0.1% NOISE/DISTORTION PERFORMANCE Total Harmonic Distortion Input Voltage Noise Input Current Noise Differential Gain Error (NTSC) Differential Phase Error (NTSC) Crosstalk DC PERFORMANCE Input Offset Voltage Conditions G = +1 G = +2, RL = 150 W G = -1, VO = 4 V Step VO = 2 V p-p G = -1, VO = 2 V Step fC = 5 MHz, VO = 2 V p-p, G = +2, RL = 1 kW f = 10 kHz f = 10 kHz G = +2, RL = 150 W to 2.5 V G = +2, RL = 150 W to 2.5 V f = 5 MHz, RL = 1 kW, G = +2 TMIN -TMAX Offset Drift Input Bias Current TMIN -TMAX Input Offset Current Open-Loop Gain INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Common-Mode Rejection Ratio OUTPUT CHARACTERISTICS Output Voltage Swing Output Voltage Swing: Output Voltage Swing: Output Current Short Circuit Current Capacitive Load Drive POWER SUPPLY Operating Range Quiescent Current Power Supply Rejection Ratio OPERATING TEMPERATURE RANGE Specifications subject to change without notice. 8 2 0.2 94 88 225 1.6 -0.2 to 4 90 0.03 to 4.975 0.075 to 4.91 0.25 to 4.65 30 45 85 40 RL = 1 kW TMIN -TMAX 82 VCM = 0 V to 3.5 V RL = 10 kW to 2.5 V RL = 1 kW to 2.5 V RL = 150 W to 2.5 V TMIN -TMAX, VOUT = 0.5 V to 4.5 V Sourcing Sinking G = +2 80 0.25 to 4.75 0.55 to 4.4 3 VS = 0, +5 V, 1 V 70 -40 11 80 -2- REV. B SPECIFICATIONS (@ T = +25 C, V = +3 V, R = 2 k A S L to 1.5 V, unless otherwise noted.) Min 80 110 AD8044A Typ 135 10 150 22 35 55 -48 16 600 0.13 0.3 -60 1.5 5.5 7.5 4.5 4.5 1.2 AD8044 Max Units MHz MHz V/ms MHz ns ns dB nV//Hz fA//Hz % Degrees dB mV mV mV/C mA mA mA dB dB kW pF V dB V V V mA mA mA pF 12 12.5 +70 V mA dB C Parameter DYNAMIC PERFORMANCE -3 dB Small Signal Bandwidth, VO < 0.5 V p-p Bandwidth for 0.1 dB Flatness Slew Rate Full Power Response Settling Time to 1% Settling Time to 0.1% NOISE/DISTORTION PERFORMANCE Total Harmonic Distortion Input Voltage Noise Input Current Noise Differential Gain Error (NTSC) Differential Phase Error (NTSC) Crosstalk DC PERFORMANCE Input Offset Voltage Conditions G = +1 G = +2, RL = 150 W G = -1, VO = 2 V Step VO = 2 V p-p G = -1, VO = 2 V Step fC = 5 MHz, VO = 2 V p-p, G = -1, RL = 100 W f = 10 kHz f = 10 kHz G = +2, RL = 150 W to 1.5 V, Input VCM = 0.5 V G = +2, RL = 150 W to 1.5 V, Input VCM = 0.5 V f = 5 MHz, RL = 1 kW, G = +2 TMIN -TMAX Offset Drift Input Bias Current TMIN -TMAX Input Offset Current Open-Loop Gain INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Common-Mode Rejection Ratio OUTPUT CHARACTERISTICS Output Voltage Swing Output Voltage Swing: Output Voltage Swing: Output Current Short Circuit Current Capacitive Load Drive POWER SUPPLY Operating Range Quiescent Current Power Supply Rejection Ratio OPERATING TEMPERATURE RANGE Specifications subject to change without notice. 8 2 0.2 92 88 225 1.6 -0.2 to 2 90 RL = 1 kW TMIN -TMAX 80 VCM = 0 V to 1.5 V RL = 10 kW to 1.5 V RL = 1 kW to 1.5 V RL = 150 W to 1.5 V TMIN -TMAX, VOUT = 0.5 V to 2.5 V Sourcing Sinking G = +2 76 0.025 to 2.98 0.17 to 2.82 0.06 to 2.93 0.35 to 2.55 0.15 to 2.75 25 30 50 35 3 VS = 0, +3 V, +0.5 V 70 0 10.5 80 REV. B -3- AD8044-SPECIFICATIONS (@ T = +25 C, V = A S 5 V, RL = 2 k to 0 V, unless otherwise noted.) Min 85 150 AD8044A Typ 160 15 190 29 30 40 -72 16 900 0.06 0.15 -60 1.4 6.5 9 4.5 4.5 1.2 Max Units MHz MHz V/ms MHz ns ns dB nV//Hz fA//Hz % Degrees dB mV mV mV/C mA mA mA dB dB kW pF V dB V V V mA mA mA pF V mA dB C Parameter DYNAMIC PERFORMANCE -3 dB Small Signal Bandwidth, VO < 0.5 V p-p Bandwidth for 0.1 dB Flatness Slew Rate Full Power Response Settling Time to 0.1% Settling Time to 0.01% NOISE/DISTORTION PERFORMANCE Total Harmonic Distortion Input Voltage Noise Input Current Noise Differential Gain Error (NTSC) Differential Phase Error (NTSC) Crosstalk DC PERFORMANCE Input Offset Voltage Conditions G = +1 G = +2, RL = 150 W G = -1, VO = 8 V Step VO = 2 V p-p G = -1, VO = 2 V Step fC = 5 MHz, VO = 2 V p-p, G = +2 f = 10 kHz f = 10 kHz G = +2, RL = 150 W G = +2, RL = 150 W f = 5 MHz, RL = 1 kW, G = +2 TMIN -TMAX Offset Drift Input Bias Current TMIN -TMAX Input Offset Current Open-Loop Gain INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Common-Mode Rejection Ratio OUTPUT CHARACTERISTICS Output Voltage Swing Output Voltage Swing: Output Voltage Swing: Output Current Short Circuit Current Capacitive Load Drive POWER SUPPLY Operating Range Quiescent Current Power Supply Rejection Ratio OPERATING TEMPERATURE RANGE Specifications subject to change without notice. 10 2 0.2 96 92 225 1.6 -5.2 to 4 90 RL = 1 kW TMIN -TMAX 82 VCM = -5 V to 3.5 V RL = 10 kW RL = 1 kW RL = 150 W TMIN -TMAX, VOUT = -4.5 V to +4.5 V Sourcing Sinking G = +2 76 -4.6 to +4.6 -4.0 to +3.8 -4.97 to +4.97 -4.85 to +4.85 -4.5 to +4.5 30 60 100 40 12 13.6 +85 3 VS = -5, +5 V, 1 V 70 -40 11.5 80 -4- REV. B AD8044 ABSOLUTE MAXIMUM RATINGS 1 MAXIMUM POWER DISSIPATION (W) Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +12.6 V Internal Power Dissipation2 Plastic DIP Package (N) . . . . . . . . . . . . . . . . . . . 1.6 Watts Small Outline Package (R) . . . . . . . . . . . . . . . . . . 1.0 Watts Input Voltage (Common-Mode) . . . . . . . . . . . . . . VS 0.5 V Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . 3.4 V Output Short Circuit Duration . . . . . . . . . . . . . . . . . . . . . . Observe Power Derating Curves Storage Temperature Range (N, R) . . . . . . . -65C to +125C Lead Temperature Range (Soldering 10 sec) . . . . . . . . +300C NOTES 1 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. 2 Specification is for the device in free air: 14-Lead Plastic Package: qJA = 75C/W 14-Lead SOIC Package: qJA = 120C/W While the AD8044 is internally short-circuit protected, this may not be sufficient to guarantee that the maximum junction temperature (+150C) is not exceeded under all conditions. To ensure proper operation, it is necessary to observe the maximum power derating curves. 2.5 TJ = +150 C 2.0 14-LEAD PLASTIC DIP PACKAGE 1.5 14-LEAD SOIC 1.0 MAXIMUM POWER DISSIPATION The maximum power that can be safely dissipated by the AD8044 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. Exceeding this limit temporarily may 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. 0.5 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 AMBIENT TEMPERATURE ( C) 80 90 Figure 3. Maximum Power Dissipation vs. Temperature ORDERING GUIDE Model AD8044AN AD8044AR-14 AD8044AR-14-REEL AD8044AR-14-REEL7 AD8044ARZ-14* AD8044ARZ-14-REEL* AD8044ARZ-14-REEL7* *Z = Pb free part Temperature Range -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C Package Description 14-Lead PDIP 14-Lead SOIC 14-Lead SOIC 13" REEL 14-Lead SOIC 7" REEL 14-Lead Plastic SOIC 14-Lead SOIC 13" REEL 14-Lead SOIC 7" REEL Package Option N-14 R-14 R-14 R-14 R-14 R-14 R-14 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 the AD8016 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. WARNING! ESD SENSITIVE DEVICE REV. B -5- AD8044-Typical Performance Characteristics 11 10 9 NUMBER OF PARTS IN BIN 100 OPEN-LOOP GAIN (dB) 8 7 6 5 4 3 2 1 VS = +5V TA = +25 C 62 PARTS MEAN = 350 V STD DEVIATION = 560 V 95 90 85 VS = +5V T = +25 C 80 75 0 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 VOS (mV) 70 1 1.5 2 2.5 3 0 250 500 750 1000 1250 1500 LOAD RESISTANCE ( ) 1750 2000 Figure 4. Typical Distribution of VOS Figure 7. Open-Loop Gain vs. RL to +2.5 V 15 MEAN = 7.9 V/ C STD DEV = 2.3 V/ C SAMPLE SIZE = 62 VS = +5 100 VS = +5V RL = 1k TO +2.5V 97 OPEN-LOOP GAIN (dB) 12 NUMBER OF PARTS IN BIN 9 94 6 91 3 88 0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 VOS DRIFT ( V/ C) 85 -40 -20 0 20 40 60 TEMPERATURE ( C) 80 100 Figure 5. VOS Drift Over -40 C to +85 C Figure 8. Open-Loop Gain vs. Temperature 2.4 VS = +5V INPUT BIAS CURRENT ( A) 100 90 80 RL = 500 VS = +5V 2.2 OPEN-LOOP GAIN (dB) 70 60 50 40 30 20 10 RL = 50 2.0 1.8 0 -45 -35 -25 -15 -5 5 15 25 35 45 55 TEMPERATURE ( C) 65 75 85 0 0 0.15 0.35 0.75 1.25 1.75 2.25 2.75 3.25 3.75 4.45 4.65 4.85 5 OUTPUT VOLTAGE (V) Figure 6. IB vs. Temperature Figure 9. Open-Loop Gain vs. Output Voltage -6- REV. B AD8044 300 INPUT VOLTAGE NOISE (nV/ Hz) 100 30 0.03 0.02 0.01 0.00 -0.01 -0.02 -0.03 -0.04 DIFF GAIN (%) VS = +5V G = +2 RL = 150 0 10 DIFF PHASE (Degrees) 10 20 30 40 50 60 70 80 90 100 3 1 10 100 1k 10k 100k FREQUENCY (Hz) 1M 10M 0.20 0.15 0.10 0.05 0.00 -0.05 -0.10 -0.15 -0.20 0 VS = +5V G = +2 RL = 150 10 20 30 40 50 60 70 80 MODULATING RAMP LEVEL (IRE) 90 100 Figure 10. Input Voltage Noise vs. Frequency Figure 13. Differential Gain and Phase Errors -30 VO = 2V p-p TOTAL HARMONIC DISTORTION (dBc) -40 -50 -60 -70 -80 -90 VS = +3V, RL = 100 AV = -1 VS = +5V, RL = 100 AV = +2 VS = +5V, RL = 100 AV = +1 0.3 0.2 0.1 NORMALIZED GAIN (dB) 0.0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 1M VS = +5V RF = 200 RL = 150 TO 2.5V G = +2 Vi = 0.2V p-p 11.6MHz -100 1 VS = +5V, RL = 1k AV = +2 VS = +5V, RL = 1k AV = +1 2 3 4 5 67 FUNDAMENTAL FREQUENCY (MHz) 8 9 10 Figure 11. Total Harmonic Distortion 10M FREQUENCY (Hz) 100M Figure 14. 0.1 dB Gain Flatness -30 -40 -50 WORST HARMONIC (dBc) 80 10MHz 70 60 OPEN-LOOP GAIN (dB) -60 -70 -80 -90 -100 -110 -120 -130 -140 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 VS = +5V RL = 2k CL = 5pF 50 40 30 20 PHASE PHASE MARGIN (Degrees) 5MHz GAIN 180 135 90 45 1MHz VS = +5V RL = 2k TO 2.5V G = +2 10 0 -10 80MHz 0 OUTPUT VOLTAGE (V p-p) -20 30k 100k Figure 12. Worst Harmonic vs. Output Voltage 10M 1M FREQUENCY (Hz) 100M Figure 15. Open-Loop Gain and Phase Margin vs. Frequency REV. B -7- AD8044 4 3 2 CLOSED-LOOP GAIN (dB) 1 0 -1 -2 VS = +5V RL = 2k TO 2.5V CL = 5pF G = +1 VO = 0.2V p-p +85 C +25 C -40 C 70 60 50 TIME (ns) G = -1 RL = 2k VS = +3V, 0.1% VS = +5V, 0.1% AND VS = 5V, 0.1% 40 30 20 VS = +3V, 1% VS = +5V, 1% AND VS = 5V, 1% -3 -4 -5 1M 10 0 0.5 10M FREQUENCY (Hz) 100M 1 1.5 INPUT STEPS (V p-p) 2 Figure 16. Closed-Loop Frequency Response vs. Temperature Figure 19. Settling Time vs. Input Step 6 5 4 CLOSED-LOOP GAIN (dB) 0 G = +1 RL = 2k CL = 5pF VO = 0.2V p-p +3V +5V 5V CMRR (dB) -10 VS = 5V -20 -30 -40 -50 -60 VS = +3V 3 2 1 0 -1 -2 -3 -4 100k 5V +3V +5V 1M 10M FREQUENCY (Hz) 100M -70 -80 0.03 0.1 1 10 FREQUENCY (MHz) 100 500 Figure 17. Closed-Loop Frequency Response vs. Supply Figure 20. CMRR vs. Frequency 1.00 OUTPUT SATURATION VOLTAGE (V) 100 RBT = 50 0.875 0.750 VS = +5V +5V -VOH (+125 C) OUTPUT RESISTANCE ( ) 10 G = +1 VS = +5V RBT +5V -VOH (+25 C) 0.625 0.500 0.375 0.250 VOL (+125 C) +5V -VOH (-55 C) 1 VOUT 0.1 RBT = 0 0.01 0.03 0.1 1 10 FREQUENCY (MHz) 100 500 0.125 VOL (-55 C) VOL (+25 C) 0.00 0 3 6 9 12 15 18 21 LOAD CURRENT (mA) 24 27 30 Figure 18. Output Resistance vs. Frequency Figure 21. Output Saturation Voltage vs. Load Current -8- REV. B AD8044 12.0 VS = 11.5 SUPPLY CURRENT (mA) 60 5V 50 VS = +5V VS = +3V 10.5 % OVERSHOOT 11.0 40 G = +2, RS = 0 , VO = 100mV STEP RF = RG = 750 G = +1, RS = 20 , VO = 100mV STEP RF = 0, RG = G = +1, RS = 40 , VO = 100mV STEP RF = 0, RG = G = +3, RS = 0 , VO = 150mV STEP RF = 750 RG = 375 RG RF +2.5V VOUT 30 10.0 20 VIN 10 50 -2.5V RS 9.5 0 0 50 100 150 LOAD CAPACITANCE (pF) 200 250 9.0 -40 -20 0 20 40 60 TEMPERATURE ( C) 80 100 Figure 22. Supply Current vs. Temperature Figure 25. % Overshoot vs. Capacitive Load 20 10 NORMALIZED OUTPUT (dB) 3 2 0 -10 VS = +5V 1 0 -1 -2 -3 -4 -5 -6 -7 100k G = +2 RL = 150 TO 2.5V RF = 200 G = +2 -PSRR PSRR (dB) G = +5 -20 -30 -40 -50 -60 -70 -80 0.01 0.1 1 10 FREQUENCY (MHz) 100 500 +PSRR VS = +5V RL = 5k TO 2.5V RF = 2k G = +10 10M FREQUENCY (Hz) 100M 500M 1M Figure 23. PSRR vs. Frequency Figure 26. Frequency Response vs. Closed-Loop Gain 10 9 8 CROSSTALK (dB) -10 VS = 5V RL = 2k -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 0.1 VS = 5V VIN = 1V p-p G = +2 RF = 1k 7 VOUT p-p (V) 6 5 4 3 2 1 0 0.1 1 10 FREQUENCY (MHz) 100 500 RL = 100 RL = 1k 1 10 FREQUENCY (MHz) 100 400 Figure 24. Output Voltage Swing vs. Frequency Figure 27. Crosstalk (Output to Output) vs. Frequency REV. B -9- AD8044 5V 4.656V VS = +5V RL = 150 CL = 5pF G = -1 TO +2.5V 2.6V 2.55V VS = +5V G = +1 RL = 2k CL = 5pF 2.5V 2.5V 2.45V 0.211V 500mV 0V 2.4V 100 s 50mV 40ns Figure 28a. Output Swing vs. Load Reference Voltage, VS = +5 V, G = -1 Figure 30. 100 mV Step Response, VS = +5 V, G = +1 5V 4.309V VS = +5V RL = 150 TO GND CL = 5pF G = -1 3V +2.920V 2.5V 2V VIN = 3V p-p RL = 2k CL = 5pF VS = +3V G = -1 2.5V 1.5V 1V 500mV +10mV 0.5V 100 s +22mV 500mV 200 s 0V Figure 28b. Output Swing vs. Load Reference Voltage, VS = +5 V, G = -1 Figure 31. Output Swing, VS = +3 V 4.5V 1.60V VS = +5V G = +2 RL = 2k VIN = 1V p-p CL = 5pF 1.58V 1.56V 1.54V 1.52V 1.50V 1.48V 1.46V 3.5V VIN = 0.1V p-p RL = 2k CL = 5pF VS = +3V G = +1 2.5V 1.5V 1.44V 500mV 0.5V 20ns 1.42V 1.40V 20mV 20ns Figure 29. One Volt Step Response, VS = +5 V, G = +2 Figure 32. Step Response, G = +1, VIN = 100 mV -10- REV. B AD8044 Overdrive Recovery Driving Capacitance Loads Overdrive of an amplifier occurs when the output and/or input range are exceeded. The amplifier must recover from this overdrive condition. As shown in Figure 33, the AD8044 recovers within 50 ns from negative overdrive and within 25 ns from positive overdrive. VS = +5V AV = +2 RF = 2k RL = 2k VIN 2V/DIV VOUT 1V/DIV The capacitive load drive of the AD8044 can be increased by adding a low valued resistor in series with the load. Figure 35 shows the effects of a series resistor on capacitive drive for varying voltage gains. As the closed-loop gain is increased, the larger phase margin allows for larger capacitive loads with less overshoot. Adding a series resistor with lower closed-loop gains accomplishes this same effect. For large capacitive loads, the frequency response of the amplifier will be dominated by the roll-off of the series resistor and capacitive load. VCC I1 R26 Q4 Q40 R15 R2 VEE VINP VINN Q13 Q17 Q22 Q7 Q21 SIP Q2 SIN Q11 Q3 C7 VEE R5 R21 R3 Q24 I7 Q47 I11 I8 VCC Q27 C9 R23 R27 Q31 C3 VOUT I10 R39 Q5 I2 I3 Q25 Q51 Q50 Q39 Q23 VEE I9 Q36 I5 2V 1V 50ns Q8 Figure 33. Overdrive Recovery, VS + 5 V, VIN = 4 V Step Circuit Description The AD8044 is fabricated on Analog Devices' proprietary eXtra-Fast Complementary Bipolar (XFCB) process which enables the construction of PNP and NPN transistors with similar fTs in the 2 GHz-4 GHz region. The process is dielectrically isolated to eliminate the parasitic and latch-up problems caused by junction isolation. These features allow the construction of high frequency, low distortion amplifiers with low supply currents. This design uses a differential output input stage to maximize bandwidth and headroom (see Figure 34). The smaller signal swings required on the first stage outputs (nodes S1P, S1N) reduce the effect of nonlinear currents due to junction capacitances and improve the distortion performance. With this design harmonic distortion of better than -85 dB @ 1 MHz into 100 W with VOUT = 2 V p-p (Gain = +2) on a single 5 volt supply is achieved. The AD8044's rail-to-rail output range is provided by a complementary common-emitter output stage. High output drive capability is provided by injecting all output stage predriver currents directly into the bases of the output devices Q8 and Q36. Biasing of Q8 and Q36 is accomplished by I8 and I5, along with a common-mode feedback loop (not shown). This circuit topology allows the AD8044 to drive 50 mA of output current with the outputs within 0.5 V of the supply rails. On the input side, the device can handle voltages from -0.2 V below the negative rail to within 1.2 V of the positive rail. Exceeding these values will not cause phase reversal; however, the input ESD devices will begin to conduct if the input voltages exceed the rails by greater than 0.5 V. Figure 34. AD8044 Simplified Schematic REV. B -11- AD8044 1000 +5V GRAPHICS IC VS = +5V < 30% OVERSHOOT R CAPACITIVE LOAD (pF) RS 0 =1 RS =0 G 75 B 75 75 100 RG VIN 100mV STEP 10 1 RF RS CL 4 5 VOUT 75 75 75 +3V OR +5V RGB MONITOR #1 0.1 F 10 F AD8044 2 3 ACL (V/V) 6 Figure 35. Capacitive Load Drive vs. Closed-Loop Gain APPLICATIONS RGB Buffer A V+ 75 1k 1k The AD8044 can provide buffering of RGB signals that include ground while operating from a single +3 V or +5 V supply. When driving two monitors from the same RGB video source it is necessary to provide an additional driver for one of the monitors to prevent the double termination situation that the second monitor presents. This has usually required a dual-supply op amp because the level of the input signal from the video driver goes all the way to ground during horizontal blanking. In singlesupply systems it can be a major inconvenience and expense to add an additional negative supply. A single AD8044 can provide the necessary drive capability and yet does not require a negative supply in this application. Figure 36 is a schematic that uses three amplifiers out of a single AD8044 to provide buffering for a second monitor. The source of the RGB signals is shown to be from a set of three current output DACs that are within a single-supply graphics IC. This is typically the situation in most PCs and workstations that may use either a standalone triple DAC or DACs that are integrated into a larger graphics chip. During horizontal blanking, the current output from the DACs is turned off and the RGB outputs are pulled to ground by the termination resistors. If voltage sources were used for the RGB signals, then the termination resistors near the graphics IC would be in series and the rest of the circuit would remain the same. This is because a voltage source is an ac short circuit, so a series resistor is required to make the drive end of the line see 75 W to ac ground. On the other hand, a current source has a very high output impedance, so a shunt resistor is required to make the drive end of the line see 75 W to ground. In either case, the monitor terminates its end of the line with 75 W. The circuit in Figure 36 shows minimum signal degradation when using a single-supply for the AD8044. The circuit performs equally well on either a +3 V or +5 V supply. B AD8044 75 75 75 1k 1k 75 75 AD8044 C V- 1k RGB MONITOR #2 1k Figure 36. Single Supply RGB Video Driver Figure 37 is an oscilloscope photo of the circuit in Figure 36 operating from a +3 V supply and driven by the Blue signal of a color bar pattern. Note that the input and output are at ground during the horizontal blanking interval. The RGB signals are specified to output a maximum of 700 mV peak. The output of the AD8044 is 1.4 V with the termination resistors providing a divide-by-two. 500mV VIN 100 90 5s GND VOUT 10 0% GND 500mV Figure 37. +3 V, RGB Buffer -12- REV. B AD8044 Active Filters Layout Considerations Active filters at higher frequencies require wider bandwidth op amps to work effectively. Excessive phase shift produced by lower frequency op amps can significantly impact active filter performance. Figure 38 shows an example of a 2 MHz biquad bandwidth filter that uses three op amps of an AD8044 package. Such circuits are sometimes used in medical ultrasound systems to lower the noise bandwidth of the analog signal before A/D conversion. R6 1k C1 50pF R2 2k 2 1 3 5 R3 2k The specified high speed performance of the AD8044 requires careful attention to board layout and component selection. Proper RF design techniques and low-pass parasitic component selection are necessary. The PCB should have a ground plane covering all unused portions of the component side of the board to provide a low impedance path. The ground plane should be removed from the area near the input pins to reduce the stray capacitance. Chip capacitors should be used for the supply bypassing. One end should be connected to the ground plane and the other within 1/8 inch of each power pin. An additional large (0.47 mF - 10 mF) tantalum electrolytic capacitor should be connected in parallel, but not necessarily so close, to supply current for fast, large signal changes at the output. The feedback resistor should be located close to the inverting input pin in order to keep the stray capacitance at this node to a minimum. Capacitance variations of less than 1 pF at the inverting input will significantly affect high speed performance. Stripline design techniques should be used for long signal traces (greater than about 1 inch). These should be designed with a characteristic impedance of 50 W or 75 W and properly terminated at each end. R1 3k VIN R4 2k 6 7 R5 2k C2 50pF 9 8 10 VOUT AD8044 AD8044 AD8044 Figure 38. 2 MHz Biquad Band-pass Filter Using AD8044 The frequency response of the circuit is shown in Figure 39. 0 -10 GAIN (dB) -20 -30 -40 10k 100k 1M FREQUENCY (Hz) 10M 100M Figure 39. Frequency Response of 2 MHz Band-pass Biquad Filter REV. B -13- AD8044 OUTLINE DIMENSIONS 14-Lead Plastic Dual In-Line Package [PDIP] (N-14) Dimensions shown in inches and (millimeters) 0.685 (17.40) 0.665 (16.89) 0.645 (16.38) 14 1 8 7 0.295 (7.49) 0.285 (7.24) 0.275 (6.99) 0.100 (2.54) BSC 0.015 (0.38) MIN 0.180 (4.57) MAX 0.150 (3.81) 0.130 (3.30) 0.110 (2.79) SEATING PLANE 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) 0.150 (3.81) 0.135 (3.43) 0.120 (3.05) 0.022 (0.56) 0.060 (1.52) 0.018 (0.46) 0.050 (1.27) 0.014 (0.36) 0.045 (1.14) 0.015 (0.38) 0.010 (0.25) 0.008 (0.20) COMPLIANT TO JEDEC STANDARDS MO-095-AB CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN 14-Lead Standard Small Outline Package [SOIC] Narrow Body (R-14) Dimensions shown in millimeters and (inches) 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) 0.25 (0.0098) 45 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-012AB 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 -14- REV. B AD8044 Revision History Location 8/04--Data Sheet changed from Rev. A to Rev. B Page Changes to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Updated OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 REV. B -15- -16- C01060-0-8/04(B) |
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