Document
Data Sheet
Ultralow Distortion Current Feedback Differential ADC Driver
ADA4927-1/ADA4927-2
FEATURES
Extremely low harmonic distortion −105 dBc HD2 at 10 MHz −91 dBc HD2 at 70 MHz −87 dBc HD2 at 100 MHz −103 dBc HD3 at 10 MHz −98 dBc HD3 at 70 MHz −89 dBc HD3 at 100 MHz
Better distortion at higher gains than VF amplifiers Low input voltage noise: 1.4 nV/√Hz High speed
−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 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 operation 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. B
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FUNCTIONAL BLOCK DIAGRAMS
ADA4927-1
16 –VS 15 –VS 14 –VS 13 –VS
–FB 1 +IN 2 –IN 3 +FB 4
12 PD 11 –OUT 10 +OUT 9 VOCM
+VS 5 +VS 6 +VS 7 +VS 8
Figure 1.
07574-001
24 +IN1 23 –FB1 22 –VS1 21 –VS1 20 PD1 19 –OUT1
–IN1 1 +FB1 2 +VS1 3 +VS1 4 –FB2 5 +IN2 6
ADA4927-2
18 +OUT1
17 VOCM1 16 –VS2 15 –VS2 14 PD2
13 –OUT2
–IN2 7 +FB2 8 +VS2 9 +VS2 10 VOCM2 11 +OUT2 12
07574-002
–40 VOUT, dm = 2V p-p
–50
Figure 2.
SPURIOUS-FREE DYNAMIC RANGE (dBc)
–60
–70
–80
–90
–100 –110 –120
G=1 G = 10 G = 20
07574-026
–130 1
10 100 1k
FREQUENCY (MHz)
Figure 3. Spurious-Free Dynamic Range vs. Frequency at Various Gains
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.
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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............................................................................. 3 +5 V Operation............................................................................. 5 Absolute Maximum Ratings............................................................ 7 Thermal Resistance ...................................................................... 7 Maximum Power Dissipation ..................................................... 7 ESD Caution.................................................................................. 7 Pin Configurations and Function Descriptions .....