AD8264 Datasheet, PDF (1/40 Pages) Analog Devices – Quad, 235 MHz, DC-Coupled VGA and Differential Output Amplifier

Quad, 235 MHz, DC-Coupled VGA
and Differential Output Amplifier
AD8264
FEATURES
Low noise
Voltage noise: 2.3 nV/√Hz
Current noise: 2 pA/√Hz
Wide bandwidth
Small signal: 235 MHz (VGAx); 80 MHz (differential output
amplifier)
Large signal: 80 MHz (1 V p-p)
Gain range
0 to 24 dB (input to VGA output)
6 to 30 dB (input to differential output)
Gain scaling: 20 dB/V
DC-coupled
Single-ended input and differential output
Supplies: ±2.5 V to ±5 V
Low power: 140 mW per channel @ ±3.3 V
APPLICATIONS
Multichannel data acquisition
Positron emission tomography
Gain trim
Industrial and medical ultrasound
Radar receivers
OPP1
IPP1
IPN1
GNH1
OPP2
IPP2
IPN2
GNH2
OPP3
IPP3
IPN3
GNH3
OPP4
IPP4
IPN4
GNH4
FUNCTIONAL BLOCK DIAGRAM
COMM VPOS VNEG
+
PrA
6dB
–
+
PrA
–6dB
+
PrA
–6dB
+
PrA
–6dB
ATTENUATOR
–24dB TO 0dB
18dB
+ _{CH1 GAIN}
– ^CONTROL
ATTENUATOR
–24dB TO 0dB
18dB
+ _{CH2 GAIN}
– ^CONTROL
ATTENUATOR
–24dB TO 0dB
18dB
+ _{CH3 GAIN}
– ^CONTROL
ATTENUATOR
–24dB TO 0dB
18dB
+ _{CH4 GAIN}
– ^CONTROL
+
6dB
–
+
6dB
–
+
6dB
–
+
6dB
–
VGA1
VOL1
VOH1
OFS1
VGA2
VOL2
VOH2
OFS2
VGA3
VOL3
VOH3
OFS3
VGA4
VOL4
VOH4
OFS4
GENERAL DESCRIPTION
The AD8264 is a 4-channel, linear-in-dB, general-purpose
variable gain amplifier (VGA) with a preamplifier (preamp),
and a flexible differential output buffer. Intended for a broad
range of applications, dc coupling combined with wide band-
width makes this amplifier a very good pulse processor.
Each channel includes a single-ended input preamp/VGA
section to preserve the wide bandwidth and fast slew rate for low-
distortion pulse applications. A 6 dB differential output buffer
with common-mode and offset adjustments enable direct coupling
to most modern high speed analog-to-digital converters (ADCs),
using the converter reference output for perfect dc matching levels.
The −3 dB bandwidth of the preamp/VGA is dc to 235 MHz,
and the bandwidth of the differential driver is 80 MHz. The
floating gain control interface provides a precise linear-in-dB scale
of 20 dB/V and is easy to interface to a variety of external circuits.
GNLO
Figure 1.
VOCM
The gain of each channel is adjusted independently, and all
channels are referenced to a single pin, GNLO. Combined with
a multi-output, digital-to-analog converter (DAC), each section
of the AD8264 can be used for active calibration or as a trim
amplifier.
The gain range of the VGA section is 24 dB. Operation from
a dual polarity power supply enables amplification of negative
voltage pulses that are generated by current-sinking pulses into
a grounded load, such as is typical of photodiodes or photo-
multiplier tubes (PMT). Delay-free processing of wide-band
video signals is also possible. The differential output amplifier
permits convenient level shifting and interfacing to single-
supply ADCs using the VOCM and OFSx pins.
The AD8264 is available in a 40-lead, 6 mm × 6 mm LFCSP
with an operating temperature range of −40°C to +105°C.
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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
www.analog.com
Fax: [phone]
©2009 Analog Devices, Inc. All rights reserved.