Extremely low harmonic distortion
−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
Low input voltage noise: 2.3 nV/√Hz
−3 dB bandwidth of 1.4 GHz, G = 2
Slew rate: 6800 V/μs, 25% to 75%
Fast overdrive recovery of <1 ns
±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
IF and baseband gain blocks
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.
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.
Differential ADC Driver
FUNCTIONAL BLOCK DIAGRAMS
Figure 1. ADA4939-1
Figure 2. ADA4939-2
VOUT, dm = 2V p-p
Figure 3. Harmonic Distortion vs. Frequency
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.
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©2008 Analog Devices, Inc. All rights reserved.