Datasheet AD600, AD602 (Analog Devices)

Dual, Low Noise, Wideband Variable Gain Amplifiers AD600/AD602 FEATURES FUNCTIONAL BLOCK DIAGRAM 2 channels with independent gain control GAT1 Linear in dB gain response PRECISION PASSIVE SCALING GATING 2 gain ranges INPUT ATTENUATOR REFERENCE INTERFACE AD600: 0 dB to 40 dB C1HI AD602: –10 dB to +30 dB VG A1OP C1LO Accurate absolute gain: ±0.3 dB A1CM GAIN CONTROL Low input noise: 1.4 nV/√Hz INTERFACE RF2 Low distortion: −60 dBc THD at ±1 V output 2.24kΩ (AD600) 0dB –12.04dB –22.08dB –36.12dB 694Ω (AD602) High bandwidth: dc to 35 MHz (−3 dB) –6.02dB –18.06dB –30.1dB –42.14dB RF1 Stable group delay: ±2 ns A1HI 20Ω Low power: 125 mW (maximum) per amplifier FIXED-GAIN A1LO AMPLIFIER
01
Signal gating function for each amplifier 500Ω R-2R LADDER NETWORK 62.5Ω 41.07dB (AD600)
0 8-
31.07dB (AD602) Drive high speed ADCs
053 0
MIL-STD-883-compliant and DESC versions available
Figure 1. Functional Block Diagram of a Single Channel of the AD600/AD602 The gain-control interfaces are fully differential, providing an
APPLICATIONS
input resistance of ~15 MΩ and a scale factor of 32 dB/V (that
Ultrasound and sonar time-gain controls
is, 31.25 mV/dB) defined by an internal voltage reference. The
High performance audio and RF AGC systems
response time of this interface is less than 1 μs. Each channel
Signal measurement
also has an independent gating facility that optionally blocks
GENERAL DESCRIPTION
signal transmission and sets the dc output level to within a few millivolts of the output ground. The gating control input is The AD600/AD6021 dual-channel, low noise, variable gain TTL- and CMOS-compatible. amplifiers are optimized for use in ultrasound imaging systems but are applicable to any application requiring precise gain, low The maximum gain of the AD600 is 41.07 dB, and the maximum noise and distortion, and wide bandwidth. Each independent gain of the AD602 is 31.07 dB; the −3 dB bandwidth of both channel provides a gain of 0 dB to +40 dB in the AD600 and models is nominally 35 MHz, essentially independent of the −10 dB to +30 dB in the AD602. The lower gain of the AD602 gain. The SNR for a 1 V rms output and a 1 MHz noise results in an improved signal-to-noise ratio (SNR) at the output. bandwidth is typically 76 dB for the AD600 and 86 dB for the However, both products have the same 1.4 nV/√Hz input noise AD602. The amplitude response is flat within ±0.5 dB from spectral density. The decibel gain is directly proportional to the 100 kHz to 10 MHz; over this frequency range, the group delay control voltage, accurately calibrated, and supply and temper- varies by less than ±2 ns at all gain settings. ature stable. Each amplifier channel can drive 100 Ω load impedances with To achieve the difficult performance objectives, a proprietary low distortion. For example, the peak specified output is ±2.5 V circuit form, the X-AMP®, was developed. Each channel of the minimum into a 500 Ω load or ±1 V into a 100 Ω load. For a X-AMP comprises a variable attenuator of 0 dB to −42.14 dB 200 Ω load in shunt with 5 pF, the total harmonic distortion for followed by a high speed fixed gain amplifier. In this way, the a ±1 V sinusoidal output at 10 MHz is typically −60 dBc. amplifier never has to cope with large inputs and can benefit The AD600J/AD602J are specified for operation from 0°C to 70°C from the use of negative feedback to precisely define the gain and are available in 16-lead PDIP (N) and 16-lead SOIC packages. and dynamics. The attenuator is realized as a 7-stage R-2R The AD600A/AD602A are specified for operation from −40°C to ladder network having an input resistance of 100 Ω, laser +85°C and are available in 16-lead CERDIP (Q) and 16-lead SOIC trimmed to ±2%. The attenuation between tap points is 6.02 dB; packages. The AD600S/AD602S are specified for operation from the gain-control circuit provides continuous interpolation between −55°C to +125°C, are available in a 16-lead CERDIP (Q) package, these taps. The resulting control function is linear in dB. and are MIL-STD-883-compliant. The AD600S/AD602S are also available under DESC SMD 5962-94572. 1 Patented.
Rev. F 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. 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. Tel: 781.329.4700 www.analog.com Trademarks and registered trademarks are the property of their respective owners. Fax: 781.461.3113 ©2008 Analog Devices, Inc. All rights reserved.
Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION NOISE PERFORMANCE GAIN-CONTROL INTERFACE SIGNAL-GATING INPUTS COMMON-MODE REJECTION ACHIEVING 80 dB GAIN RANGE SEQUENTIAL MODE (MAXIMUM SNR) PARALLEL MODE (SIMPLEST GAIN-CONTROL INTERFACE) LOW RIPPLE MODE (MINIMUM GAIN ERROR) APPLICATIONS INFORMATION TIME-GAIN CONTROL (TGC) AND TIME-VARIABLE GAIN (TVG) INCREASING OUTPUT DRIVE DRIVING CAPACITIVE LOADS REALIZING OTHER GAIN RANGES ULTRALOW NOISE VCA LOW NOISE, 6 dB PREAMPLIFIER LOW NOISE AGC AMPLIFIER WITH 80 dB GAIN RANGE WIDE RANGE, RMS-LINEAR dB MEASUREMENT SYSTEM (2 MHz AGC AMPLIFIER WITH RMS DETECTOR) 100 dB TO 120 dB RMS RESPONDING CONSTANT BANDWIDTH AGC SYSTEMS WITH HIGH ACCURACY DECIBEL OUTPUTS 100 dB RMS/AGC SYSTEM WITH MINIMAL GAIN ERROR (PARALLEL GAIN WITH OFFSET) 120 dB RMS/AGC SYSTEM WITH OPTIMAL SNR (SEQUENTIAL GAIN) OUTLINE DIMENSIONS ORDERING GUIDE