MAX2038CCQ+ Maxim Integrated Products, MAX2038CCQ+ Datasheet - Page 14

• Manufacturer Part Number: MAX2038CCQ+
• Description: IC VGA W/OCTAL MIXER 8CH 100TQFP
• Manufacturer: Maxim Integrated Products
• Type: Variable Gain Amplifierr

Specifications of MAX2038CCQ+

• Applications: Medical Ultrasound Imaging, Sonar
• Mounting Type: Surface Mount
• Package / Case: 100-TQFP Exposed Pad, 100-eTQFP, 100-HTQFP, 100-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Ultrasound VGA Integrated
with CW Octal Mixer
The MAX2038 is an 8-channel VGA integrated with a
programmable octal quadrature mixer array designed
for ultrasound imaging and Doppler applications. The
device is optimized for efficient power consumption,
high dynamic range, and for exceptionally low noise
performance. The VGA path features differential inputs,
analog variable gain control, differential outputs for
direct ADC drive, and a selectable output voltage
clamp to avoid ADC overdrive. The integrated octal
quadrature mixer array includes serial programmable
LO phase generators for CWD beamforming applica-
tions. The LO phase dividers can be programmed for 4,
8, or 16 quadrature phases. Lowpass filters are inte-
grated at the input paths of each CW mixer. The out-
puts for the mixers are summed into single I/Q
differential current outputs.
The MAX2038 also integrates an octal quadrature mixer
array and programmable LO phase generators for a
complete continuous wave (CW) Doppler beamforming
solution. The LO phase selection for each channel is
programmed using a digital serial interface and a sin-
gle 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 in order 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 selec-
table lowpass filter for optimal CWD noise performance.
The outputs of the mixers are summed into single I and
Q differential current outputs. The mixers and LO gen-
erators are designed to have exceptionally low noise
performance of -155dBc/Hz at 1kHz offset from a
1.25MHz carrier, measured with 900mV
clutter signal.
The MAX2038’s VGAs are optimized for high linearity,
high dynamic range, and low output-noise performance,
making this component ideal for ultrasound imaging
applications. The VGA paths also exhibit a channel-to-
channel crosstalk of -80dB at 10MHz and an absolute
gain error of less than ±0.25dB for minimal channel-to-
channel focusing error in an ultrasound system. Each
VGA path includes circuitry for adjusting analog gain, an
output buffer with differential output ports (VGOUT_+,
VGOUT_-) for driving ADCs, and differential input ports
(VGIN_+, VGIN_-), which are ideal for directly interfac-
ing to the MAX2034 quad LNA. See the High-Level
Wave Mixer and Programmable Beamformer Functional
Diagram for details.
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Variable Gain Amplifier (VGA)
Detailed Description
P-P
differential
The VGA has an adjustable gain range from -12.5dB to
+29.5dB, achieving a total dynamic range of 42dB
(typ). The VGA gain can be adjusted through the differ-
ential gain control inputs VG_CTL+ and VG_CTL-. Set
the differential gain-control input voltage at +2V for min-
imum gain and -2V for maximum gain. The differential
analog control common-mode voltage is 3V (typ).
CW_FILTER
LOW_PWR
VG_CTL+
VG_CTL-
CWIN1+
CWIN8+
CWIN1-
CWIN8-
CW_VG
VGIN1+
VGIN8+
VGIN1-
VGIN8-
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PD
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Programmable Beamformer
High-Level Wave Mixer and
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V
CC
+5V
GND
_Functional Diagram
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VGA
VGA
+5V (LOW NOISE)
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MAX2038
I&Q
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I&Q
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V
REF
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50Ω
50Ω
50Ω
50Ω
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VG_CLAMP_MODE
VGOUT1+
VGOUT1-
VGOUT8+
VGOUT8-
CW_IOUT+
CW_IOUT-
CW_QOUT+
CW_QOUT-
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