ADA4927-1 AD [Analog Devices], ADA4927-1 Datasheet

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ADA4927-1

Manufacturer Part Number
ADA4927-1
Description
Ultralow Distortion Current Feedback Differential ADC Driver
Manufacturer
AD [Analog Devices]
Datasheet

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Part Number:
ADA4927-1YCPZ-R7
Manufacturer:
Cortina
Quantity:
5
FEATURES
Extremely low harmonic distortion
Better distortion at higher gains than VF amplifiers
Low input voltage noise: 1.4 nV/√Hz
High speed
Low input offset voltage: 0.3 mV typical
Externally adjustable gain
Stability and bandwidth controlled by feedback resistor
Differential-to-differential or single-ended-to-differential
Adjustable output common-mode voltage
Wide supply operation: +5 V to ±5 V
APPLICATIONS
ADC drivers
Single-ended-to-differential converters
IF and baseband gain blocks
Differential buffers
Differential line drivers
GENERAL DESCRIPTION
The ADA4927 is a low noise, ultralow distortion, high speed,
current feedback differential amplifier that is an ideal choice for
driving high performance ADCs with resolutions up to 16 bits
from dc to 100 MHz. The output common-mode level can easily be
matched to the required ADC input common-mode levels. The
internal common-mode feedback loop provides exceptional output
balance and suppression of even-order distortion products.
Differential gain configurations are easily realized using an
external feedback network comprising four resistors. The
current feedback architecture provides loop gain that is nearly
independent of closed-loop gain, achieving wide bandwidth,
low distortion, and low noise at higher gains and lower power
consumption than comparable voltage feedback amplifiers.
The ADA4927 is fabricated using the Analog Devices, Inc., silicon-
germanium complementary bipolar process, enabling very low
levels of distortion with an input voltage noise of only 1.3 nV/√Hz.
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.
−105 dBc HD2 @ 10 MHz
−91 dBc HD2 @ 70 MHz
−87 dBc HD2 @ 100 MHz
−103 dBc HD3 @ 10 MHz
−98 dBc HD3 @ 70 MHz
−89 dBc HD3 @ 100 MHz
−3 dB bandwidth of 2.3 GHz
0.1 dB gain flatness: 150 MHz
Slew rate: 5000 V/μs, 25% to 75%
Fast 0.1% settling time: 10 ns
operation
Current Feedback Differential ADC Driver
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
The low dc offset and excellent dynamic performance of the
ADA4927 make it well suited for a wide variety of data acquisition
and signal processing applications.
The ADA4927-1 is available in a Pb-free, 3 mm × 3 mm 16-lead
LFCSP, and the ADA4927-2 is available in a Pb-free, 4 mm × 4 mm
24-lead LFCSP. The pinouts are optimized to facilitate printed
circuit board (PCB) layout and to minimize distortion. They are
specified to operate over the −40°C to +105°C temperature range.
Figure 3. Spurious-Free Dynamic Range vs. Frequency at Various Gains
–100
–110
–120
–130
–40
–50
–60
–70
–80
–90
1
FUNCTIONAL BLOCK DIAGRAMS
V
OUT
ADA4927-1/ADA4927-2
+FB1
,
–FB2
+V
+V
–IN1
+IN2
dm
–FB
+FB
+IN
–IN
S1
S1
= 2V p-p
1
2
3
4
5
6
1
2
3
4
©2008 Analog Devices, Inc. All rights reserved.
Ultralow Distortion
ADA4927-1
ADA4927-2
10
FREQUENCY (MHz)
Figure 1.
Figure 2.
12 PD
11 –OUT
10 +OUT
9 V
18 +OUT1
17 V
16 –V
15 –V
14 PD2
13 –OUT2
100
OCM
OCM1
S2
S2
www.analog.com
G = 1
G = 10
G = 20
1k

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ADA4927-1 Summary of contents

Page 1

... The low dc offset and excellent dynamic performance of the ADA4927 make it well suited for a wide variety of data acquisition and signal processing applications. The ADA4927-1 is available in a Pb-free × 16-lead LFCSP, and the ADA4927-2 is available in a Pb-free × 24-lead LFCSP. The pinouts are optimized to facilitate printed circuit board (PCB) layout and to minimize distortion. They are specified to operate over the − ...

Page 2

... ADA4927-1/ADA4927-2 TABLE OF CONTENTS Features .............................................................................................. 1 Applications ....................................................................................... 1 General Description ......................................................................... 1 Functional Block Diagrams ............................................................. 1 Revision History ............................................................................... 2 Specifications ..................................................................................... 3 ±5 V Operation ............................................................................. 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 Theory of Operation ...................................................................... 16 REVISION HISTORY 10/08— ...

Page 3

... 301 Ω 301 Ω 56.2 Ω (when used Conditions V = 0.1 V p-p OUT 2.0 V p-p OUT 0.1 V p-p, ADA4927-1 OUT 0.1 V p-p, ADA4927-2 OUT step, 25% to 75% OUT step OUT 0.9 V step See Figure 45 for distortion test circuit ...

Page 4

... ADA4927-1/ADA4927 Performance OCM OUT, cm Table 2. Parameter V DYNAMIC PERFORMANCE OCM Small Signal −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 ...

Page 5

... Output Balance Error = 301 Ω 301 Ω 56.2 Ω (when used Conditions V = 0.1 V p-p OUT 2.0 V p-p OUT 0.1 V p-p, ADA4927-1 OUT 0.1 V p-p, ADA4927-2 OUT step, 25% to 75% OUT step OUT 0.15 V step See Figure 45 for distortion test circuit ...

Page 6

... ADA4927-1/ADA4927 Performance OCM OUT, cm Table 5. Parameter V DYNAMIC PERFORMANCE OCM Small signal −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 ...

Page 7

... Unit JA 2.5 87 °C/W 2.0 47 °C/W 1.5 1.0 0 –40 ESD CAUTION Rev Page ADA4927-1/ADA4927 the sum of the D ) times the quiescent current ( ADA4927-2 ADA4927-1 – 100 AMBIENT TEMPERATURE (°C) Figure 4. Maximum Power Dissipation vs. Ambient Temperature for a 4-Layer Board ). ...

Page 8

... Scale) + OCM NOTES 1. CONNECT THE EXPOSED PADDLE TO ANY PLANE BETWEEN AND INCLUDING +V AND –V S Figure 5. ADA4927-1 Pin Configuration Table 9. ADA4927-1 Pin Function Descriptions Pin No. Mnemonic Description 1 −FB Negative Output for Feedback Component Connection 2 +IN Positive Input Summing Node 3 − ...

Page 9

... R = 301 Ω 56.2 Ω (when used 10k 1k 10k 1k 10k Figure 12. Large Signal Frequency Response for Various Temperatures Rev Page ADA4927-1/ADA4927 kΩ, unless otherwise noted p-p OUT dm 0 –3 – 301Ω – 10 442Ω ...

Page 10

... ADA4927-1/ADA4927 100mV p-p OUT dm 0 –3 – 200Ω L – 1kΩ L – 100 FREQUENCY (MHz) Figure 13. Small Signal Frequency Response for Various Loads 100mV p-p OUT dm 0 –3 – –4V OCM V = –3.5V OCM –9 OCM V = +3.5V OCM V = +4V OCM – ...

Page 11

... HD2, 10MHz –110 HD3, 10MHz –120 –4 0.6 0.8 1.0 1.2 Figure 24. Harmonic Distortion vs. V Rev Page ADA4927-1/ADA4927 p-p OUT dm HD2 HD3 HD2 HD3 HD2 HD3 100 FREQUENCY (MHz p-p ...

Page 12

... ADA4927-1/ADA4927-2 – ±2.5V S –50 –60 –70 –80 –90 –100 –110 –120 –130 1 10 FREQUENCY (MHz) Figure 25. Harmonic Distortion vs. Frequency at Various V – p-p OUT dm –50 –60 –70 –80 –90 –100 –110 –120 –130 1 10 FREQUENCY (MHz) Figure 26. Spurious-Free Dynamic Range vs. Frequency at Various Gains – ...

Page 13

... –5 –10 1k 0.1 Figure 35. Closed-Loop Output Impedance Magnitude vs. Frequency –5 – 10M 100M Rev Page ADA4927-1/ADA4927-2 MAGNITUDE PHASE 1k 10k 100k 1M 10M 100M 1G 10G FREQUENCY (Hz ± ± ±2.5V ...

Page 14

... ADA4927-1/ADA4927 –10 –20 –30 –40 –50 – TIME (ns) Figure 37. Small Signal Pulse Response –10 –20 –30 –40 –50 – TIME (ns) Figure 38. V Small Signal Pulse Response OCM 1.2 1.0 0.8 0.6 0.4 0.2 0 –0.2 – ...

Page 15

... FILTER 56.2Ω V ADA4927 OCM 0.1µF 301Ω 25.5Ω 0.1µF –5V 301Ω Figure 45. Test Circuit for Distortion Measurements Rev Page ADA4927-1/ADA4927-2 1kΩ DIFFERENTIAL NETWORK ANALYZER INPUT 50Ω DIFFERENTIAL NETWORK ANALYZER INPUT 50Ω 200Ω 50Ω 442Ω HP ...

Page 16

... ADA4927-1/ADA4927-2 THEORY OF OPERATION The ADA4927 differs from conventional operational amplifiers in that it has two outputs whose voltages move in opposite directions and an additional input Moreover, the ADA4927 OCM uses a current feedback architecture. Like a traditional current feedback op amp, the ADA4927 relies on high open-loop trans- impedance, T(s), and negative current feedback to force the outputs to the desired voltages ...

Page 17

... G1 1/2 (4kTR ) G2 1/2 (4kTR ) F1 1/2 (4kTR ) F2 Rev Page ADA4927-1/ADA4927 modeled as a differential input, and the nIN and i , appear between each input and nIN− nIN+ is obtained by multiplying nIN (defined in the G equation). The N N pin When the feedback OCM nCM is common mode. Each of the four ...

Page 18

... ADA4927-1/ADA4927-2 Table 12. Differential Input, DC-Coupled Nominal Gain (dB) R (Ω 301 20 442 26 604 Table 13. Single-Ended Ground-Referenced Input, DC-Coupled, R Nominal Gain (dB) R (Ω 309 301 20 511 39.2 26 806 || Similar to the case of a conventional op amp, the output noise voltage densities can be estimated by multiplying the input- referred terms at +IN and − ...

Page 19

... F source resistance R is equal to R ⎞ ⎟ 348 ⎟ = 464 Ω ⎟ 348 ⎟ × 348 348 ) ⎠ Rev Page ADA4927-1/ADA4927 348Ω 464Ω 50Ω 348Ω ADA4927 OCM R G 348Ω ...

Page 20

... ADA4927-1/ADA4927 ||R = 26.5 Ω. Note that p-p, which was obtained with R circuit with the Thevenin equivalent (closest 1% value used for the terminated source and R TH loop is shown in Figure 53 348Ω 26.7Ω 348Ω ...

Page 21

... Power-Down in Cold Applications The power-down feature should not be used in applications in which the ambient temperature falls below 0°C. Contact sales for information regarding applications that require the power- down feature to be used at ambient temperatures below 0°C. Rev Page ADA4927-1/ADA4927-2 ...

Page 22

... ADA4927-1 was addressed. The first requirement is a solid ground plane that covers as much of the board area around the ADA4927-1 as possible. However, clear the area near the feedback resistors (RF), gain resistors (RG), and the input summing nodes (Pin 2 and Pin 3) of all ground and power planes (see Figure 55) ...

Page 23

... V ADA4927 OCM 39.2Ω 24.3Ω 30nH 0.1µF 0.1µF 38.3Ω 511Ω Rev Page ADA4927-1/ADA4927-2 pin of the ADA4927 is bypassed for noise reduction OCM 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 ADA4927-1YCPZ-R2 −40°C to +105°C 1 ADA4927-1YCPZ-RL −40°C to +105°C 1 ADA4927-1YCPZ-R7 −40°C to +105°C 1 ADA4927-2YCPZ-R2 −40°C to +105°C 1 ADA4927-2YCPZ-RL −40°C to +105°C 1 ADA4927-2YCPZ-R7 −40°C to +105° RoHS Compliant Part. ...

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