AD600/AD602: Dual, Low Noise, Wideband Variable Gain Amplifiers Data Handbook Specifications Owner's Manual

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Dual, Low Noise, Wideband Variable Gain Amplifiers

AD600/AD602

FEATURES FUNCTIONAL BLOCK DIAGRAM

2 channels with independent gain control GAT1

Linear in d B gain response PRECISION PASSIVE

SCALING GATING

INPUT ATTENUATOR

REFERENCE INTERFACE

2 gain ranges

AD600: 0 d B to 40 d B C1HI VG A1OP

AD602: –10 d B to +30 d B C1LO

Accurate absolute gain: ±0.3 d B GAIN CONTROL INTERFACE

Low input noise: 1.4 n V/√Hz 2.24kΩ (AD600)

0d B –12.04d B –22.08d B –36.12d B 694Ω (AD602)

Low distortion: −60 d Bc THD at ±1 V output

–6.02d B –18.06d B –30.1d B –42.14d B RF1

A1HI 20Ω

High bandwidth: dc to 35 MHz (−3 d B)

FIXED-GAIN

Stable group delay: ±2 ns A1LO AMPLIFIER

500Ω R-2R LADDER NETWORK 62.5Ω 41.07d B (AD600)

Low power: 125 m W (maximum) per amplifier 31.07d B (AD602) Signal gating function for each amplifier

Figure 1.

Drives high speed ADCs

MIL-STD-883-compliant and DESC versions available The gain-control interfaces are fully differential, providing an input resistance of ~15 MΩ and a scale factor of 32 d B/V (that APPLICATIONS is, 31.25 m V/d B) defined by an internal voltage reference. The response time of this interface is less than 1 μs. Each channel

Ultrasound and sonar time-gain controls

also has an independent gating facility that optionally blocks

High performance audio and RF AGC systems

signal transmission and sets the dc output level to within a few

Signal measurement

millivolts of the output ground. The gating control input is TTL- and CMOS-compatible.

GENERAL DESCRIPTION

The maximum gain of the AD600 is 41.07 d B, and the

The AD600/AD6021 dual channel, low noise, variable gain

maximum gain of the AD602 is 31.07 d B; the −3 d B bandwidth

amplifiers are optimized for use in ultrasound imaging systems

of both models is nominally 35 MHz, essentially independent of

but are applicable to any application requiring precise gain, low

the gain. The SNR for a 1 V rms output and a 1 MHz noise

noise and distortion, and wide bandwidth. Each independent

bandwidth is typically 76 d B for the AD600 and 86 d B for the

channel provides a gain of 0 d B to +40 d B in the AD600 and

AD602. The amplitude response is flat within ±0.5 d B from

−10 d B to +30 d B in the AD602. The lower gain of the AD602

100 k Hz to 10 MHz; over this frequency range, the group delay

results in an improved signal-to-noise ratio (SNR) at the output.

varies by less than ±2 ns at all gain settings.

However, both products have the same 1.4 n V/√Hz input noise spectral density. The decibel gain is directly proportional to the

Each amplifier channel can drive 100 Ω load impedances with

control voltage, accurately calibrated, and supply and

low distortion. For example, the peak specified output is ±2.5 V

temperature stable.

minimum into a 500 Ω load or ±1 V into a 100 Ω load. For a 200 Ω load in shunt with 5 p F, the total harmonic distortion for 8-

To achieve the difficult performance objectives, a proprietary

a ±1 V sinusoidal output at 10 MHz is typically −60 d Bc.

circuit form, the X-AMP®, was developed. Each channel of the X-AMP comprises a variable attenuator of 0 d B to −42.14 d B

The AD600J/AD602J are specified for operation from 0°C to 70°C

followed by a high speed fixed gain amplifier. In this way, the

and are available in 16-lead PDIP (N) and 16-lead SOIC_W

amplifier never has to cope with large inputs and can benefit

packages. The AD600A/AD602A are specified for operation from

from the use of negative feedback to precisely define the gain

−40°C to +85°C and are available in 16-lead CERDIP (Q) and

and dynamics. The attenuator is realized as a 7-stage R-2R

16-lead SOIC_W packages. The AD600S/ AD602S are specified

ladder network having an input resistance of 100 Ω, laser

for operation from −55°C to +125°C, are available in a 16-lead

trimmed to ±2%. The attenuation between tap points is 6.02 d B;

CERDIP (Q) package, and are MIL-STD-883-compliant. The

the gain-control circuit provides continuous interpolation between

AD600S/AD602S are also available under DESC SMD 5962-94572.

these taps. The resulting control function is linear in d B.

1 Patented.

Rev. E 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

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