Rainbow Electronics MAX2038 - Manual

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
specification of -70dBc at V
OUT = 1.5V P-P and f IN =
5MHz and an ultrasound-specific*, two-tone, third-order
intermodulation distortion specification of -52dBc at
V
OUT = 1.5V P-P and f IN = 5MHz.
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
♦ 8-Channel Configuration
♦ High Integration for Ultrasound Imaging
Applications
♦ Pin Compatible with the MAX2037 Ultrasound VGA
VGA Features
♦ 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
♦ ±0.25dB Absolute Gain Error
♦ 120mW Consumption per Channel
♦ Switchable Output VGA Clamp Eliminating ADC
Overdrive
♦ Fully Differential VGA Outputs for Direct ADC
Drive
♦ Variable Gain Range Achieves 42dB Dynamic
Range
♦ -70dBc HD2 at V
OUT = 1.5V P-P and f IN = 5MHz
♦ Two-Tone Ultrasound-Specific* IMD3 of
-52dBc at V OUT = 1.5V P-P and f IN = 5MHz
CW Doppler Mixer Features
♦ Low Mixer Noise of -155dBc/Hz at 1kHz Offset
from 1.25MHz Carrier
♦ Serial-Programmable LO Phase Generator for 4, 8,
16 LO Quadrature Phase Resolution
♦ Optional Individual Channel 4 x f
LO LO Input
Drive Capability
♦ 269mW Power Consumption per Channel (Normal
Power Mode) and 226mW Power Consumption
per Channel (Low-Power Mode)
♦ CWD Implementation Is Fully Compliant with All
Patents Related to Ultrasound Imaging
Techniques
MAX2038
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.