General Description

The MAX2038 8-channel variable-gain amplifier (VGA)

and programmable octal mixer array is designed for

high linearity, high dynamic range, and low noise per-

formance targeting ultrasound imaging and Doppler

applications. Each amplifier features differential inputs

and outputs and a total gain range of 42dB (typ). In

addition, the VGAs offer very low output-referred noise

performance suitable for interfacing with 12-bit ADCs.

The MAX2038 VGA is optimized for less than ±0.25dB

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

amplifier’s output to limit the output signals, thereby

preventing 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 MAX2038 also integrates an octal quadrature mixer

array and programmable LO phase generators for a

complete CW beamforming solution. The LO phase

selection for each channel can be programmed using a

digital serial interface and a single high-frequency clock

or the LOs for each complex mixer pair can be directly

driven using separate 4 x LO clocks. The serial interface

is designed to allow multiple devices to be easily daisy

chained to minimize program interface wiring. The LO

phase dividers can be programmed to allow 4, 8, or 16

quadrature phases. The input path of each CW mixer

consists of a selectable lowpass filter for optimal CWD

noise performance. The outputs of the mixers are

summed into I and Q differential current outputs. The

mixers and LO generators are designed to have excep-

tionally low noise performance of -155dBc/Hz at 1kHz

offset from a 1.25MHz carrier.

The MAX2038 operates from a +5.0V power supply,

consuming only 120mW/channel in VGA mode and

269mW/channel in normal power CW mode. A low-

power CW mode is also available and consumes only

226mW/channel. The device is available in a lead-free

100-pin TQFP package (14mm x 14mm x 1mm) with an

exposed pad. 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 MAX2037 Ultrasound VGA

VGA Features

o Maximum Gain, Gain Range, and Output-Referred

Noise Optimized for Interfacing with 12-Bit ADCs

Maximum Gain of 29.5dB

Total Gain Range of 42dB

22nV/

√√Hz Ultra-Low Output-Referred Noise at

5MHz

o ±0.25dB Absolute Gain Error

o 120mW Consumption per Channel

o Switchable Output VGA Clamp Eliminating ADC

Overdrive

o Fully Differential VGA Outputs for Direct ADC

Drive

o Variable Gain Range Achieves 42dB Dynamic

Range

o Two-Tone Ultrasound-Specific* IMD3 of

CW Doppler Mixer Features

o Low Mixer Noise of -155dBc/Hz at 1kHz Offset

from 1.25MHz Carrier

o Serial-Programmable LO Phase Generator for 4, 8,

16 LO Quadrature Phase Resolution

Drive Capability

o 269mW Power Consumption per Channel (Normal

Power Mode) and 226mW Power Consumption

per Channel (Low-Power Mode)

o CWD Implementation Is Fully Compliant with All

Patents Related to Ultrasound Imaging

Techniques

Ultrasound VGA Integrated

with CW Octal Mixer

________________________________________________________________

Maxim Integrated Products

1

Ordering Information

19-4375; Rev 0; 1/09

EVALUATION

KIT

AVAILABLE

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

+

Denotes a lead(Pb)-free/RoHS-compliant package.

D = Dry packing.

T = Tape and reel.

*

EP = Exposed pad.

PART

TEMP RANGE

PIN-PACKAGE

MAX2038CCQ+D

0

°C to +70°C

100 TQFP-EP*

MAX2038CCQ+TD

0

°C to +70°C

100 TQFP-EP*

Pin Configuration appears at end of data sheet.

*

See the Ultrasound-Specific IMD3 Specification in the

Applications Information section.