AD8264ACPZ-RL

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 OPP1 IPP1 IPN1 GNH1 FUNCTIONAL BLOCK DIAGRAM COMM VPOS VNEG VGA1 + PrA 6dB – ATTENUATOR –24dB TO 0dB 18dB + 6dB – VOL1 VOH1 OFS1 VGA2 18dB + 6dB – VOL2 VOH2 OFS2 VGA3 + PrA 6dB – ATTENUATOR –24dB TO 0dB + CH3 GAIN – CONTROL 18dB + 6dB – VOL3 VOH3 OFS3 VGA4 + PrA 6dB – ATTENUATOR –24dB TO 0dB + – 18dB + 6dB – VOL4 VOH4 OFS4 07736-001 OPP2 IPP2 IPN2 GNH2 OPP3 IPP3 IPN3 GNH3 + PrA 6dB – + CH1 GAIN CONTROL – ATTENUATOR –24dB TO 0dB + CH2 GAIN – CONTROL APPLICATIONS Multichannel data acquisition Positron emission tomography Gain trim Industrial and medical ultrasound Radar receivers OPP4 IPP4 IPN4 GNH4 CH4 GAIN CONTROL GNLO VOCM Figure 1. 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 bandwidth 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 lowdistortion 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. 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 photomultiplier tubes (PMT). Delay-free processing of wide-band video signals is also possible. The differential output amplifier permits convenient level shifting and interfacing to singlesupply 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: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2009 Analog Devices, Inc. All rights reserved. AD8264 TABLE OF CONTENTS Features .............................................................................................. 1  Applications ....................................................................................... 1  Functional Block Diagram .............................................................. 1  General Description ......................................................................... 1  Revision History ............................................................................... 2  Specifications..................................................................................... 3  Absolute Maximum Ratings............................................................ 6  Thermal Resistance ...................................................................... 6  Maximum Power Dissipation ..................................................... 6  ESD Caution .................................................................................. 6  Pin Configuration and Function Descriptions ............................. 7  Typical Performance Characteristics ............................................. 8  Test Circuits ..................................................................................... 20 Theory of Operation ...................................................................... 28  Overview ..................................................................................... 28  Preamp ......................................................................................... 28  VGA ............................................................................................. 28  Post Amplifier ............................................................................. 29  Noise ............................................................................................ 29  Applications Information .............................................................. 30  A Low Channel Count Application Concept Using a Discrete Reference ..................................................................................... 30  A DC Connected Concept Example ........................................ 31  Evaluation Board ............................................................................ 34  Connecting and Using the AD8264-EVALZ .......................... 34  Outline Dimensions ....................................................................... 38  Ordering Guide .......................................................................... 38  REVISION HISTORY 5/09—Revision 0: Initial Version Rev. 0 | Page 2 of 40 AD8264 SPECIFICATIONS VS = ±2.5 V, TA = 25°C, f = 10 MHz, CL = 5 pF, RL = 500 Ω per output (VGAx, VOHx, VOLx), VGAIN = (VGNHx − VGNLO) = 0 V, VVOCM = GND, VOFSx = GND, gain range = 6 dB to 30 dB, unless otherwise specified. Table 1. Parameter GENERAL PERFORMANCE –3 dB Small Signal Bandwidth (VGAx) –3 dB Large Signal Bandwidth (VGAx) –3 dB Small Signal Bandwidth (Differential Output)1 –3 dB Large Signal Bandwidth (Differential Output)1 Slew Rate Conditions VOUT = 10 mV p-p VOUT = 1 V p-p VOUT = 100 mV p-p VOUT = 2 V p-p VGAx, VOUT = 2 V p-p VGAx, VOUT = 1 V p-p Differential output, VOUT = 2 V p-p Differential output, VOUT = 1 V p-p Pins IPPx Pins IPPx at dc; ΔVIN/ΔIBIAS Pins IPPx Pins IPPx at 10 MHz Min Typ 235 150 80 80 380 290 470 220 −5 4.2 2 7.9 2.3 2 9 72 45 3.5