General Description

The MAX2035 8-channel variable-gain amplifier (VGA)

is designed for high linearity, high dynamic range, and

low-noise performance targeting ultrasound imaging

and Doppler applications. Each amplifier features dif-

ferential inputs and outputs and a total gain range of

typically 50dB. In addition, the VGAs offer very low out-

put-referred noise performance suitable for interfacing

with 10-bit ADCs.

The MAX2035 VGA is optimized for less than ±0.5dB

absolute gain error to ensure minimal channel-to-chan-

nel ultrasound beamforming focus error. The device’s

differential outputs are designed to directly drive ultra-

sound ADCs through an external passive anti-aliasing

filter. A switchable clamp is also provided at each ampli-

fier’s outputs to limit the output signals, thereby prevent-

ing ADC overdrive or saturation.

Dynamic performance of the device is optimized to

reduce distortion to support second-harmonic imaging.

The device achieves a second-harmonic distortion

5MHz, and an ultrasound-specific* two-tone third-order

intermodulation distortion specification of -52dBc at

The MAX2035 operates from a +5.0V power supply,

consuming only 127mW/channel. The device is avail-

able in a 100-pin TQFP package with an exposed paddle.

Electrical performance is guaranteed over a 0°C to

+70°C temperature range.

Applications

Ultrasound Imaging

Sonar

Features

o 8-Channel Configuration

o High Integration for Ultrasound Imaging

Applications

o Pin Compatible with the MAX2036 Ultrasound

VGA Plus CW Doppler Beamformer

o Maximum Gain, Gain Range, and Output-Referred

Noise Optimized for Interfacing with 10-Bit ADCs

Maximum Gain of 39.5dB

Total Gain Range of 50dB

60nV/

√

√Hz Ultra-Low Output-Referred Noise at

5MHz

Pin-for-Pin 12-Bit Compatibility Supported By

MAX2037/MAX2038

o ±0.5dB Absolute Gain Error

o Switchable Output VGA Clamp Eliminating ADC

Overdrive

o Fully Differential VGA Outputs for Direct ADC

Drive

o Variable Gain Range Achieves 50dB Dynamic

Range

o Two-Tone Ultrasound-Specific* IMD3 of -52dBc at

o 127mW Consumption per Channel

*

See the Ultrasound-Specific IMD3 Specification in the

Applications Information section.

Ultrasound Variable-Gain Amplifier

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Maxim Integrated Products

1

Ordering Information

19-0630; Rev 0; 10/06

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

+

Denotes lead-free package.

T

= Tape-and-reel package.

D

= Dry packing.

PART

TEMP

RANGE

PIN-PACKAGE

PKG

CODE

MAX2035CCQ-D

0°C to +70°C

100 TQFP-EP†

(14mm x 14mm)

C100E-3

MAX2035CCQ-TD

0°C to +70°C

100 TQFP-EP†

(14mm x 14mm)

C100E-3

MAX2035CCQ+D

0°C to +70°C

100 TQFP-EP†

(14mm x 14mm)

C100E-3

MAX2035CCQ+TD 0°C to +70°C

100 TQFP-EP†

(14mm x 14mm)

C100E-3

Functional Diagram

MAX2035

BIAS

CIRCUITRY

GND

EXT_RES

PD

VG_CTL+

VG_CTL-

VG_CLAMP_MODE

VG_OUT1+

VG_OUT1-

VG_OUT8+

VG_OUT8-

VG_IN1+

VG_IN1-

VG_IN8+

VG_IN8-

-10.5dB TO +39.5dB

VGA

50Ω

50Ω

VGA

50Ω

50Ω

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