19-0630; Rev 0; 10/06
Ultrasound Variable-Gain Amplifier
MAX2035
General Description
Features
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.
ꢀ 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
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.
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 ꢀrror
ꢀ Switchable Output VGA Clamp ꢀliminating ADC
Dynamic performance of the device is optimized to
reduce distortion to support second-harmonic imaging.
The device achieves a second-harmonic distortion
Overdrive
ꢀ Fully Differential VGA Outputs for Direct ADC
specification of -62dBc at V
= 1.5V
and f
=
IN
OUT
P-P
Drive
5MHz, and an ultrasound-specific* two-tone third-order
intermodulation distortion specification of -52dBc at
ꢀ Variable Gain Range Achieves 50dB Dynamic
Range
V
OUT
= 1.5V
and f = 5MHz.
P-P IN
ꢀ -62dBc HD2 at V
= 1.5V and f = 5MHz
P-P IN
OUT
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.
ꢀ Two-Tone Ultrasound-Specific* IMD3 of -52dBc at
= 1.5V and f = 5MHz
V
OUT
P-P
IN
ꢀ 127mW Consumption per Channel
*See the Ultrasound-Specific IMD3 Specification in the
Applications Information section.
Applications
Ultrasound Imaging
Sonar
Ordering Information
Functional Diagram
TꢀMP
RANGꢀ
PKG
CODꢀ
V
CC
V
REF
PART
PIN-PACKAGꢀ
†
100 TQFP-EP
MAX2035
MAX2035CCQ-D
0°C to +70°C
C100E-3
C100E-3
C100E-3
C100E-3
VG_CTL+
VG_CTL-
VG_IN1+
VG_IN1-
-10.5dB TO +39.5dB
(14mm x 14mm)
VG_CLAMP_MODE
VG_OUT1+
†
100 TQFP-EP
MAX2035CCQ-TD 0°C to +70°C
MAX2035CCQ+D 0°C to +70°C
MAX2035CCQ+TD 0°C to +70°C
50Ω
50Ω
VGA
VGA
(14mm x 14mm)
VG_OUT1-
•
•
•
†
100 TQFP-EP
(14mm x 14mm)
•
•
•
•
•
•
•
•
•
•
•
•
50Ω
VG_IN8+
VG_IN8-
VG_OUT8+
VG_OUT8-
†
100 TQFP-EP
(14mm x 14mm)
50Ω
BIAS
CIRCUITRY
†
EP = Exposed paddle.
+Denotes lead-free package.
T = Tape-and-reel package.
D = Dry packing.
PD
GND
EXT_RES
________________________________________________________________ Maxim Integrated Products
1
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.