MAX2035 Datasheet, PDF (1/12 Pages) Maxim Integrated Products – Ultrasound Variable-Gain Amplifier

19-0630; Rev 0; 10/06
Ultrasound Variable-Gain Amplifier
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 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 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 -62dBc HD2 at V_OUT = 1.5V_P-P and f_IN = 5MHz
o Two-Tone Ultrasound-Specific* IMD3 of -52dBc at
V_OUT = 1.5V_P-P and f_IN = 5MHz
o 127mW Consumption per Channel
*See the Ultrasound-Specific IMD3 Specification in the
Applications Information section.
Functional Diagram
VCC
VREF
VG_CTL+
VG_CTL-
VG_IN1+
VG_IN1-
•
•
•
VG_IN8+
VG_IN8-
PD
MAX2035
-10.5dB TO +39.5dB
VGA
50Ω
••
••
••
VGA
50Ω
•
•
•
50Ω
50Ω
BIAS
CIRCUITRY
VG_CLAMP_MODE
VG_OUT1+
VG_OUT1-
•
•
•
VG_OUT8+
VG_OUT8-
GND
EXT_RES
Ordering Information
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
†_{EP = Exposed paddle.}
+Denotes lead-free package.
T = Tape-and-reel package.
D = Dry packing.
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