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AD603AR 参数 Datasheet PDF下载

AD603AR图片预览
型号: AD603AR
PDF下载: 下载PDF文件 查看货源
内容描述: 低噪声, 90 MHz可变增益放大器 [Low Noise, 90 MHz Variable Gain Amplifier]
分类和应用: 放大器
文件页数/大小: 20 页 / 602 K
品牌: AD [ ANALOG DEVICES ]
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Low Noise, 90 MHz
Variable Gain Amplifier
AD603
FEATURES
Linear-in-dB gain control
Pin programmable gain ranges
−11 dB to +31 dB with 90 MHz bandwidth
9 dB to 51 dB with 9 MHz bandwidth
Any intermediate range, for example −1 dB to +41 dB
with 30 MHz bandwidth
Bandwidth independent of variable gain
1.3 nV/√Hz input noise spectral density
±0.5 dB typical gain accuracy
impedance (50 MΩ), low bias (200 nA) differential input; the
scaling is 25 mV/dB, requiring a gain control voltage of only 1 V
to span the central 40 dB of the gain range. An overrange and
underrange of 1 dB is provided whatever the selected range. The
gain control response time is less than 1 µs for a 40 dB change.
The differential gain control interface allows the use of either
differential or single-ended positive or negative control voltages.
Several of these amplifiers may be cascaded and their gain
control gains offset to optimize the system S/N ratio.
The AD603 can drive a load impedance as low as 100 Ω with
low distortion. For a 500 Ω load in shunt with 5 pF, the total
harmonic distortion for a ±1 V sinusoidal output at 10 MHz is
typically −60 dBc. The peak specified output is ±2.5 V
minimum into a 500 Ω load.
The AD603 uses a patented proprietary circuit topology—the
X-AMP®. The X-AMP comprises a variable attenuator of 0 dB
to −42.14 dB followed by a fixed-gain amplifier. Because of the
attenuator, the amplifier never has to cope with large inputs and
can use negative feedback to define its (fixed) gain and dynamic
performance. The attenuator has an input resistance of 100 Ω,
laser trimmed to ±3%, and comprises a seven-stage R-2R ladder
network, resulting in an attenuation between tap points of
6.021 dB. A proprietary interpolation technique provides a
continuous gain control function which is linear in dB.
The AD603 is specified for operation from −40°C to +85°C.
APPLICATIONS
RF/IF AGC amplifier
Video gain control
A/D range extension
Signal measurement
GENERAL DESCRIPTION
The AD603 is a low noise, voltage-controlled amplifier for use
in RF and IF AGC systems. It provides accurate, pin selectable
gains of −11 dB to +31 dB with a bandwidth of 90 MHz or 9 dB
to 51 dB with a bandwidth of 9 MHz. Any intermediate gain
range may be arranged using one external resistor. The input
referred noise spectral density is only 1.3 nV/√Hz and power
consumption is 125 mW at the recommended ±5 V supplies.
The decibel gain is linear in dB, accurately calibrated, and stable
over temperature and supply. The gain is controlled at a high
FUNCTIONAL BLOCK DIAGRAM
VPOS
8
VNEG
6
GPOS
1
V
G
GNEG
2
GAIN-
CONTROL
INTERFACE
6.44kΩ
1
5
SCALING
REFERENCE
PRECISION PASSIVE
INPUT ATTENUATOR
FIXED-GAIN
AMPLIFIER
7
V
OUT
AD603
FDBK
694Ω
1
0dB
VINP
3
R
2R
COMM
4
R-2R LADDER NETWORK
00539-001
–6.02dB
R
–12.04dB –18.06dB –24.08dB
R
2R
2R
R
2R
R
–30.1dB
R
2R
–36.12dB –42.14dB
R
2R
R
20Ω
1
1
NOMINAL
VALUES.
Figure 1.
Rev. G
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
Fax: 781.461.3113
© 2005 Analog Devices, Inc. All rights reserved.