ADA4950-1 Datasheet, PDF (1/28 Pages) Analog Devices – Low Power, Selectable Gain Differential ADC Driver, G = 1, 2, 3

Low Power, Selectable Gain
Differential ADC Driver, G = 1, 2, 3
ADA4950-1/ADA4950-2
FEATURES
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
APPLICATIONS
ADC drivers
Single-ended-to-differential converters
IF and baseband gain blocks
Differential buffers
Line drivers
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 single-
ended-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
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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
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FUNCTIONAL BLOCK DIAGRAMS
+INB 1
+INA 2
–INA 3
+INB 4
ADA4950-1
12 PD
11 –OUT
10 +OUT
9 V_OCM
Figure 1. ADA4950-1
–INA1 1
–INB1 2
+V_S1 3
+V_S1 4
+INB2 5
+INA2 6
ADA4950-2
18 +OUT1
17 V_OCM1
16 –V_S2
15 –VS2
14 PD2
13 –OUT2
Figure 2. ADA4950-2
–40
V_{OUT, dm} = 2V p-p
–50
–60
HD2, ±5V
HD3, ±5V
–70
HD2, ±2.5V
HD3, ±2.5V
–80
–90
–100
–110
–120
–130
–140
0.1
1
10
100
FREQUENCY (MHz)
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.
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