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
specification of -62dBc at VOUT = 1.5VP-P and fIN =
5MHz, and an ultrasound-specific* two-tone third-order
intermodulation distortion specification of -52dBc at
VOUT = 1.5VP-P and fIN = 5MHz.
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 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 MAX2036 Ultrasound
VGA Plus CW Doppler Beamformer
♦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
♦±0.5dB Absolute Gain Error
♦Switchable Output VGA Clamp Eliminating ADC
Overdrive
♦Fully Differential VGA Outputs for Direct ADC
Drive
♦Variable Gain Range Achieves 50dB Dynamic
Range
♦-62dBc HD2 at VOUT = 1.5VP-P and fIN = 5MHz
♦Two-Tone Ultrasound-Specific* IMD3 of -52dBc at
VOUT = 1.5VP-P and fIN = 5MHz
♦127mW Consumption per Channel
*
See the Ultrasound-Specific IMD3 Specification in the
Applications Information section.
MAX2035
Ultrasound Variable-Gain Amplifier
________________________________________________________________
Maxim Integrated Products
1
Ordering Information
19-0630; Rev 1; 2/09
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.
†
EP = Exposed pad.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
-
Denotes a package containing lead(Pb).
T = Tape and reel.
D = Dry packing.