ada4939-1 Analog Devices, Inc., ada4939-1 Datasheet

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ada4939-1

Manufacturer Part Number
ada4939-1
Description
Ultralow Distortion Differential Adc Driver
Manufacturer
Analog Devices, Inc.
Datasheet

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Part Number:
ada4939-1YCPZ-R7
Manufacturer:
Analog Devices Inc
Quantity:
1 948
FEATURES
Extremely low harmonic distortion
Low input voltage noise: 2.3 nV/√Hz
High speed
±0.5 mV typical offset voltage
Externally adjustable gain
Stable for differential gains ≥2
Differential-to-differential or single-ended-to-differential
Adjustable output common-mode voltage
Single-supply operation: 3.3 V to 5 V
APPLICATIONS
ADC drivers
Single-ended-to-differential converters
IF and baseband gain blocks
Differential buffers
Line drivers
GENERAL DESCRIPTION
The ADA4939 is a low noise, ultralow distortion, high speed
differential amplifier. It is an ideal choice for driving high
performance ADCs with resolutions up to 16 bits from dc to
100 MHz. The output common-mode voltage is user adjustable
by means of an internal common-mode feedback loop, allowing
the ADA4939 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.
With the ADA4939, differential gain configurations are easily
realized with a simple external feedback network of four resistors
that determine the closed-loop gain of the amplifier.
The ADA4939 is fabricated using Analog Devices, Inc., proprietary
silicon-germanium (SiGe), complementary bipolar process,
enabling it to achieve very low levels of distortion with an input
voltage noise of only 2.3 nV/√Hz. The low dc offset and excellent
dynamic performance of the ADA4939 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.
−102 dBc HD2 @ 10 MHz
−83 dBc HD2 @ 70 MHz
−77 dBc HD2 @ 100 MHz
−101 dBc HD3 @ 10 MHz
−97 dBc HD3 @ 70 MHz
−91 dBc HD3 @ 100 MHz
−3 dB bandwidth of 1.4 GHz, G = 2
Slew rate: 6800 V/μs, 25% to 75%
Fast overdrive recovery of <1 ns
operation
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
The ADA4939 is available in a Pb-free, 3 mm × 3 mm 16-lead
LFCSP (ADA4939-1, single) or a Pb-free, 4 mm × 4 mm 24-lead
LFCSP (ADA4939-2, dual). The pinout has been optimized to
facilitate PCB layout and minimize distortion. The ADA4939-1
and the ADA4939-2 are specified to operate over the −40°C to
+105°C temperature range; both operate on supplies between
3.3 V and 5 V.
–100
–105
–110
–60
–65
–70
–75
–80
–85
–90
–95
1
FUNCTIONAL BLOCK DIAGRAMS
V
OUT, dm
Figure 3. Harmonic Distortion vs. Frequency
ADA4939-1/ADA4939-2
+FB1
HD2
HD3
Differential ADC Driver
–FB2
+V
+V
–IN1
+IN2
–FB
+FB
+IN
–IN
S1
S1
= 2V p-p
1
2
3
4
5
6
1
2
3
4
Figure 1. ADA4939-1
Figure 2. ADA4939-2
©2008 Analog Devices, Inc. All rights reserved.
Ultralow Distortion
ADA4939-1
ADA4939-2
FREQUENCY (MHz)
10
12 PD
11 –OUT
10 +OUT
9 V
18 +OUT1
17 V
16 –V
15 –V
14 PD2
13 –OUT2
OCM
OCM1
S2
S2
www.analog.com
100

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ada4939-1 Summary of contents

Page 1

... FREQUENCY (MHz) Figure 3. Harmonic Distortion vs. Frequency The ADA4939 is available in a Pb-free × 16-lead LFCSP (ADA4939-1, single Pb-free × 24-lead LFCSP (ADA4939-2, dual). The pinout has been optimized to facilitate PCB layout and minimize distortion. The ADA4939-1 and the ADA4939-2 are specified to operate over the −40°C to +105° ...

Page 2

... ADA4939-1/ADA4939-2 TABLE OF CONTENTS Features .............................................................................................. 1 Applications....................................................................................... 1 General Description ......................................................................... 1 Functional Block Diagrams............................................................. 1 Revision History ............................................................................... 2 Specifications..................................................................................... Operation ............................................................................... 3 3.3 V Operation ............................................................................ 5 Absolute Maximum Ratings............................................................ 7 Thermal Resistance ...................................................................... 7 Maximum Power Dissipation ..................................................... 7 ESD Caution.................................................................................. 7 Pin Configurations and Function Descriptions ........................... 8 Typical Performance Characteristics ............................................. 9 Test Circuits..................................................................................... 15 Operational Description................................................................ 16 Definition of Terms.................................................................... 16 REVISION HISTORY 5/08— ...

Page 3

... Linear Output Current Output Balance Error / 402 Ω 200 Ω 60.4 Ω (when used Conditions V = 0.1 V p-p OUT 0.1 V p-p, ADA4939-1 OUT 0.1 V p-p, ADA4939-2 OUT p-p OUT p-p, 25% to 75% OUT 1.5 V step 3.16 IN See Figure 41 for distortion test circuit ...

Page 4

... ADA4939-1/ADA4939 Performance OCM OUT, cm Table 2. Parameter V DYNAMIC PERFORMANCE OCM −3 dB Bandwidth Slew Rate Input Voltage Noise (RTI) V INPUT CHARACTERISTICS OCM Input Voltage Range Input Resistance Input Offset Voltage V CMRR OCM Gain General Performance Table 3. Parameter POWER SUPPLY Operating Range ...

Page 5

... Linear Output Current Output Balance Error = +V / 402 Ω 200 Ω 60.4 Ω (when used Conditions V = 0.1 V p-p OUT 0.1 V p-p, ADA4939-1 OUT 0.1 V p-p, ADA4939-2 OUT p-p OUT p-p, 25% to 75% OUT 1.0 V step 3.16 IN See Figure 41 for distortion test circuit V ...

Page 6

... ADA4939-1/ADA4939 Performance OCM OUT, cm Table 5. Parameter V DYNAMIC PERFORMANCE OCM −3 dB Bandwidth Slew Rate Input Voltage Noise (RTI) V INPUT CHARACTERISTICS OCM Input Voltage Range Input Resistance Input Offset Voltage V CMRR OCM Gain General Performance Table 6. Parameter POWER SUPPLY Operating Range ...

Page 7

... EIA/JESD 51-7. Table 8. Thermal Resistance Package Type ADA4939-1, 16-Lead LFCSP (Exposed Pad) ADA4939-2, 24-Lead LFCSP (Exposed Pad) MAXIMUM POWER DISSIPATION The maximum safe power dissipation in the ADA4939 package is limited by the associated rise in junction temperature (T the die. At approximately 150° ...

Page 8

... PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS PIN 1 INDICATOR 12 PD –FB 1 ADA4939-1 + –OUT TOP VIEW – +OUT (Not to Scale) + Figure 5. ADA4939-1 Pin Configuration Table 9. ADA4939-1 Pin Function Descriptions Pin No. Mnemonic 1 −FB 2 +IN 3 − OCM 10 +OUT 11 − ...

Page 9

... Figure 12. Large Signal Frequency Response for Various Temperatures Rev Page ADA4939-1/ADA4939 kΩ, unless otherwise noted p-p OUT 200Ω 60.4Ω +2. 127Ω 66.3Ω ...

Page 10

... ADA4939-1/ADA4939 100mV p-p OUT –1 –2 –3 –4 –5 –6 –7 –8 –9 – 1kΩ L – 200Ω L – 100 FREQUENCY (MHz) Figure 13. Small Signal Frequency Response for Various Loads 100mV p-p OUT –3 – ...

Page 11

... HD2 10MHz HD3 10MHz –65 HD2 70MHz HD3 70MHz –70 1 Rev Page ADA4939-1/ADA4939-2 HD2, V HD3, V HD2, V HD3 p-p) OUT, dm and Supply Voltage MHz OUT p-p OUT ±2. ...

Page 12

... ADA4939-1/ADA4939-2 – HD2 p-p OUT HD3 p-p OUT HD2 p-p –70 OUT HD3 p-p OUT, dm –80 –90 –100 –110 –120 1 10 FREQUENCY (MHz) Figure 25. Harmonic Distortion vs. Frequency at Various Output Voltages – 200Ω –40 –50 –60 –70 –80 –90 –100 ...

Page 13

... L –110 –120 –130 –140 100 Rev Page ADA4939-1/ADA4939-2 – 200Ω –50 –60 –70 INPUT AMP 1 TO OUTPUT AMP 2 –80 –90 INPUT AMP 2 TO OUTPUT AMP 100 FREQUENCY (MHz) Figure 34. Crosstalk vs. Frequency for ADA4939-2 ...

Page 14

... ADA4939-1/ADA4939-2 3.5 3.0 V OUT, dm 2.5 2.0 PD 1.5 1.0 0.5 0 –0.5 0 100 200 300 400 500 600 TIME (ns) Figure 37. PD Response Time R = 200Ω 100 700 800 900 1000 Rev Page 100 1k 10k 100k FREQUENCY (Hz) Figure 38. Voltage Noise Spectral Density, RTI 1M 10M ...

Page 15

... LOW-PASS FILTER V ADA4939 60.4Ω OCM 0.1µF 200Ω 0.1µF 402Ω Figure 41. Test Circuit for Distortion Measurements Rev Page ADA4939-1/ADA4939-2 1kΩ NETWORK ANALYZER INPUT 49.9Ω AC-COUPLED 50Ω 49.9Ω 200Ω 50Ω 442Ω 2:1 DUAL FILTER CT 261Ω ...

Page 16

... ADA4939-1/ADA4939-2 OPERATIONAL DESCRIPTION DEFINITION OF TERMS – +IN –OUT + ADA4939 OCM –D IN –IN +OUT +FB Figure 42. Circuit Definitions Differential Voltage Differential voltage refers to the difference between two node voltages. For example, the output differential voltage (or equivalently, output differential-mode voltage) is defined as ...

Page 17

... Table 11 summarizes the input noise sources, the F G multiplication factors, and the output-referred noise density terms. V nRG1 can also OCM V nRG2 Rev Page ADA4939-1/ADA4939 and feedback resistors modeled as a differential input, and the and i , appear between each input and nIN+ is obtained by multiplying nIN ...

Page 18

... ADA4939-1/ADA4939-2 Table 11. Output Noise Voltage Density Calculations for Matched Feedback Networks Input Noise Contribution Input Noise Term Differential Input v nIN Inverting Input i nIN Noninverting Input i nIN V Input v OCM nCM Gain Resistor nRG1 Gain Resistor nRG2 Feedback Resistor ...

Page 19

... Figure 46 indicates this open-circuit voltage. V OUT The input impedance must be calculated using the formula OUT, dm Rev Page ADA4939-1/ADA4939-2 . The common-mode G and R in the lower loop. This voltage is present the upper loop and partially bootstrapping R G ⎛ ⎛ ⎞ ...

Page 20

... ADA4939-1/ADA4939 order to match the 50 Ω source resistance, the termi- nation resistor calculated using R T The closest standard 1% value for 400Ω 50Ω 50Ω 200Ω 60.4Ω V ADA4939 OCM 2V p 200Ω ...

Page 21

... The input impedance of the V ADA4939 devices share one reference output recommended that a buffer be used. must G includes the G Rev Page ADA4939-1/ADA4939 (−V )]/2. Because of this S S pin sources and sinks current, depending OCM input is driven OCM ...

Page 22

... PCB design. This section shows a detailed example of how the ADA4939-1 was addressed. The first requirement is a solid ground plane that covers as much of the board area around the ADA4939-1 as possible. However, the area near the feedback resistors ( and the input summing nodes (Pin 2 and Pin 3) should be G cleared of all ground and power planes (see Figure 51) ...

Page 23

... V ADA4939 OCM 24.3Ω 200Ω 30nH 0.1µF 0.1µF 27.4Ω 412Ω Rev Page ADA4939-1/ADA4939-2 pin of the ADA4939 is bypassed for noise reduction 5V (A) 3.3V (A) 3.3V (D) AVDD2 AVDD1 DRVDD VIN– AD9445 BUFFER T/H 47pF 14 ADC VIN+ CLOCK/ ...

Page 24

... SEATING PLANE ORDERING GUIDE Model Temperature Range 1 ADA4939-1YCPZ-R2 −40°C to +105°C 1 ADA4939-1YCPZ-RL −40°C to +105°C 1 ADA4939-1YCPZ-R7 −40°C to +105°C 1 ADA4939-2YCPZ-R2 −40°C to +105°C 1 ADA4939-2YCPZ-RL −40°C to +105°C 1 ADA4939-2YCPZ-R7 −40°C to +105° RoHS Compliant Part. ...

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