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ADA4950-1 Dataheets PDF



Part Number ADA4950-1
Manufacturers Analog Devices
Logo Analog Devices
Description (ADA4950-1/-2) Low Power Selectable Gain Differential ADC Driver
Datasheet ADA4950-1 DatasheetADA4950-1 Datasheet (PDF)

Low Power, Selectable Gain Differential ADC Driver, G = 1, 2, 3 ADA4950-1/ADA4950-2 FEATURES www.datasheet4u.com High performance at low power High speed −3 dB bandwidth of 750 MHz, G = 1 0.1 dB flatness to 210 MHz, VOUT, dm = 2 V p-p, RL, dm = 200 Ω Slew rate: 2900 V/μs, 25% to 75% Fast 0.1% settling time of 9 ns Low power: 9.5 mA per amplifier Low harmonic distortion 108 dB SFDR @ 10 MHz 98 dB SFDR @ 20 MHz Low output voltage noise: 9.2 nV/√Hz, G = 1, RTO ±0.2 mV typical input offset voltage S.

  ADA4950-1   ADA4950-1


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Low Power, Selectable Gain Differential ADC Driver, G = 1, 2, 3 ADA4950-1/ADA4950-2 FEATURES www.datasheet4u.com High performance at low power High speed −3 dB bandwidth of 750 MHz, G = 1 0.1 dB flatness to 210 MHz, VOUT, dm = 2 V p-p, RL, dm = 200 Ω Slew rate: 2900 V/μs, 25% to 75% Fast 0.1% settling time of 9 ns Low power: 9.5 mA per amplifier Low harmonic distortion 108 dB SFDR @ 10 MHz 98 dB SFDR @ 20 MHz Low output voltage noise: 9.2 nV/√Hz, G = 1, RTO ±0.2 mV typical input offset voltage Selectable differential gains of 1, 2, and 3 Differential-to-differential or single-ended-to-differential operation Adjustable output common-mode voltage Input common-mode range shifted down by 1 VBE Wide supply range: +3 V to ±5 V Available in 16-lead and 24-lead LFCSP packages FUNCTIONAL BLOCK DIAGRAMS 16 –VS 15 –VS 13 –VS 12 PD 11 –OUT 10 +OUT 9 VOCM +INB 1 +INA 2 –INA 3 +INB 4 ADA4950-1 14 –VS +VS 7 +VS 8 +VS 5 Figure 1. ADA4950-1 +INA1 +INB1 –VS1 –VS1 PD1 –OUT1 –INA1 –INB1 +VS1 +VS1 +INB2 +INA2 1 2 3 4 5 6 24 23 22 21 20 19 +VS 6 ADA4950-2 18 17 16 15 14 13 +OUT1 VOCM1 –VS2 –VS2 PD2 –OUT2 HARMONIC DISTORTION (dBc) ADC drivers Single-ended-to-differential converters IF and baseband gain blocks Differential buffers Line drivers Figure 2. ADA4950-2 –40 –50 –60 –70 –80 –90 –100 –110 –120 –130 1 10 FREQUENCY (MHz) 100 07957-025 VOUT, dm = 2V p-p GENERAL DESCRIPTION The ADA4950-1/ADA4950-2 are gain-selectable versions of the ADA4932-1/ADA4932-2 with on-chip feedback and gain resistors. They are ideal choices for driving high performance ADCs as singleended-to-differential or differential-to-differential amplifiers. The output common-mode voltage is user adjustable by means of an internal common-mode feedback loop, allowing the ADA4950-1/ ADA4950-2 output to match the input of the ADC. The internal feedback loop also provides exceptional output balance as well as suppression of even-order harmonic distortion products. Differential gain configurations of 1, 2, and 3 are easily realized with internal feedback networks that are connected externally to set the closed-loop gain of the amplifier. The ADA4950-1/ADA4950-2 are fabricated using the Analog Devices, Inc., proprietary silicon-germanium (SiGe) complementary bipolar process, enabling them to achieve low levels of distortion and noise at low power consumption. The low offset and excellent dynamic performance of the ADA4950-x make it well suited for a wide variety of data acquisition and signal processing applications. Rev. 0 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. HD2, ±5V HD3, ±5V HD2, ±2.5V HD3, ±2.5V –140 0.1 Figure 3. Harmonic Distortion vs. Frequency at Various Supplies The ADA4950-x is available in a Pb-free, 3 mm × 3 mm, 16-lead LFCSP (ADA4950-1, single) or a Pb-free, 4 mm × 4 mm, 24-lead LFCSP (ADA4950-2, dual). The pinout has been optimized to facilitate PCB layout and minimize distortion. The ADA4950-1/ ADA4950-2 are specified to operate over the −40°C to +105°C temperature range; both operate on supplies from +3 V to ±5 V. 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 ©2009 Analog Devices, Inc. All rights reserved. –INA2 –INB2 +VS2 +VS2 VOCM2 +OUT2 07957-002 APPLICATIONS 7 8 9 10 11 12 07957-001 ADA4950-1/ADA4950-2 TABLE OF CONTENTS Features .............................................................................................. 1  Applications ....................................................................................... 1  www.datasheet4u.com Theory of Operation ...................................................................... 18  Applications Information .............................................................. 19  Analyzing an Application Circuit ............................................ 19  Selecting the Closed-Loop Gain............................................... 19  Estimating the Output Noise Voltage ...................................... 19  Calculating the Input Impedance for an Application Circuit ....................................................................................................... 20  Input Common-Mode Voltage Range ..................................... 22  Input and Output Capacitive AC Coupling ............................ 22  Input Signal Swing Considerations .......................................... 22  Setting the Output Common-Mode Voltage .......................... 22  Layout, Grounding, and Bypassing .............................................. 23  Hig.


C5909 ADA4950-1 ADA4950-2


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