AD AD9675

Octal Ultrasound AFE
with JESD204B
Preliminary Technical Data
The AD9675 is designed for low cost, low power, small size,
and ease of use for medical ultrasound. It contains eight
channels of a variable gain amplifier (VGA) with a low noise
preamplifier (LNA), a CW harmonic rejection I/Q demodulator
with programmable phase rotation, an anti-aliasing filter
(AAF), an analog-to-digital converter (ADC), a digital highpass filter and an RF decimation by 2.
8 channels of LNA, VGA, AAF, ADC, and digital RF decimator
Low power: 150 mW per channel, TGC mode, 40 MSPS;
65mW per channel, CW mode; <30mW at power-up
10 mm × 10 mm, 144-ball CSP-BGA
TGC channel input-referred noise: 0.8 nV/√Hz, max gain
Flexible power-down modes
Fast recovery from low power standby mode: <2 μs
Overload recovery: <10 ns
Low noise preamplifier (LNA)
Input-referred noise: 0.78 nV/√Hz, gain = 21.6 dB
Programmable gain: 15.6 dB/17.9 dB/21.6 dB
0.1 dB compression: 1000 mV p-p/750 mV p-p/450 mV p-p
Flexible active input impedance matching
Variable gain amplifier (VGA)
Attenuator range: 45dB, Linear-in-dB gain control
Postamp gain (PGA): 21 dB/24 dB/27 dB/30 dB
Antialiasing filter (AAF)
Programmable second-order LPF from 8 MHz to 18 MHz or
13.5MHz to 30MHz and HPF
Analog-to-digital converter (ADC)
SNR: 75dB, 14 bits up to 125 MSPS
JESD204B Subclass 0 coded serial digital outputs
CW mode harmonic rejection I/Q demodulator
Individual programmable phase rotation
Output dynamic range per channel: >160 dBc/√Hz
Output-referred SNR: 156 dBc/√Hz, 1 kHz offset, −3dBFS
RF digital high-pass filter and decimation by 2
Each channel features a maximum gain of up to 52 dB, a fully
differential signal path, and an active input preamplifier
termination. The channel is optimized for high dynamic
performance and low power in applications where a small
package size is critical.
The LNA has a single-ended-to-differential gain that is selectable
through the SPI. Assuming a 15 MHz noise bandwidth (NBW)
and a 21.6 dB LNA gain, the LNA input SNR is 94 dB. In CW
Doppler mode, each LNA output drives an I/Q demodulator
that has independently programmable phase rotation with 16
phase settings.
Power-down of individual channels is supported to increase
battery life for portable applications. Standby mode allows quick
power-up for power cycling. In CW Doppler operation, the
VGA, AAF, and ADC are powered down. The ADC contains
several features designed to maximize flexibility and minimize
system cost, such as a programmable clock, data alignment, and
programmable digital test pattern generation. The digital test
patterns include built-in fixed patterns, built-in pseudo random
patterns, and custom user-defined test patterns entered via the
serial port interface.
Figure 1.
Rev. PrB
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© Analog Devices, Inc. All rights reserved.
Preliminary Technical Data
©2013 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
Rev. PrB | Page 2 of 2