AD8337 Datasheet, PDF (1/28 Pages) Analog Devices – General-Purpose, Low Cost, DC-Coupled VGA

FEATURES
Low noise
Voltage noise = 2.2 nV/√Hz
Current noise = 4.8 pA/√Hz (positive input)
Wide bandwidth (−3 dB) = 280 MHz
Nominal gain range
0 dB to 24 dB (preamp gain = 6 dB)
Gain scaling
19.7 dB/V
DC-coupled
Single-ended input and output
High speed uncommitted op amp input
Supplies: +5 V, ±2.5 V, or ±5 V
Low power: +78 mW with ±2.5 V supplies
APPLICATIONS
Gain trim
PET scanners
High performance AGC systems
I/Q signal processing
Video
Industrial and medical ultrasound
Radar receivers
GENERAL DESCRIPTION
The AD8337 is a low noise, single-ended, linear-in-dB, general-
purpose variable gain amplifier usable at frequencies from
dc to 100 MHz; the −3 dB bandwidth is 280 MHz. Excellent
bandwidth uniformity across the entire gain range and low
output-referred noise makes the AD8337 ideal for gain trim
applications and for driving high speed ADCs.
Excellent dc characteristics combined with high speed make
the AD8337 particularly suited for industrial ultrasound, PET
scanners, and video applications. Dual-supply operation enables
gain control of negative-going pulses such as generated by
photodiodes or photomultiplier tubes.
The AD8337 uses the popular and versatile ADI exclusive
X-AMP® architecture with a gain range of 24 dB. The gain
control interface provides precise linear-in-dB scaling of
19.7 dB/V, referenced to VCOM.
General-Purpose, Low Cost,
DC-Coupled VGA
AD8337
FUNCTIONAL BLOCK DIAGRAM
VPOS
8
AD8337
GAIN 7
GAIN CONTROL
INTERFACE
18dB
1 VOUT
INPP 3
PREAMP
(PRA)
+
INPN 4 ^–
VCOM 2
5
PRAO
8 SECTIONS
6
VNEG
Figure 1.
The AD8337 includes an uncommitted operational current-
feedback preamplifier (PrA) that operates in inverting or
noninverting configurations. Using external resistors, the
device can be configured for gains of 6 dB or greater. The
AD8337 is characterized with a noninverting PrA gain of 2×
using two external 100 Ω resistors. The attenuator has a
range of 24 dB, and the output amplifier has a fixed gain of
8× (18.06 dB). The lowest nominal gain range is 0 dB to 24 dB
and can be shifted up or down by adjusting the preamp gain.
Multiple AD8337s can be connected in series for larger gain
ranges and to provide for interstage filtering to suppress noise
and distortion and for nulling offset voltages.
The operating temperature range of the AD8337 is –40°C to
+85°C, and it is available in an 8-lead, 3 mm × 3 mm, chip scale
package (LFCSP).
Rev. A
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