Octal Ultrasound AFE with JESD204B
Data Sheet
AD9675
FEATURES
GENERAL DESCRIPTION
8 channels of LNA, VGA, AAF, ADC, and digital RF decimator
Low power
150 mW per channel, TGC mode, 40 MSPS
62.5 mW per channel, CW mode
10 mm × 10 mm, 144-ball CSP_BGA
TGC channel input referred noise: 0.82 nV/√Hz,
maximum gain
Flexible power-down modes
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 continuous wave (CW) harmonic rejection I/Q
demodulator with programmable phase rotation, an antialiasing
filter (AAF), an analog-to-digital converter (ADC), and a digital
high-pass filter and RF decimation by 2 for data processing and
bandwidth reduction.
Fast recovery from low power standby mode: 2 μs
Low noise preamplifier (LNA)
Each channel features a maximum gain of up to 52 dB, a fully
differential signal path, and an active input preamplifier termina-
tion. The channel is optimized for high dynamic performance
and low power in applications where a small package size is critical.
Input referred noise: 0.78 nV/√Hz, gain = 21.6 dB
Programmable gain: 15.6 dB, 17.9 dB, or 21.6 dB
0.1 dB compression: 1000 mV p-p, 750 mV p-p, or 450 mV p-p
Flexible active input impedance matching
Variable gain amplifier (VGA)
Attenuator range: 45 dB, linear in dB gain control
Postamp gain (PGA): 21 dB, 24 dB, 27 dB, or 30 dB
Antialiasing filter (AAF)
The LNA has a single-ended to differential gain that is selectable
through the serial port interface (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.
Programmable second-order low-pass filter (LPF) from
8 MHz to 18 MHz or 13.5 MHz to 30 MHz and high-pass
filter (HPF)
Analog-to-digital converter (ADC)
SNR: 75 dB, 14 bits up to 125 MSPS
JESD204B Subclass 0 coded serial digital outputs
CW Doppler mode harmonic rejection I/Q demodulator
Individual programmable phase rotation
Dynamic range per channel: 160 dBFS/√Hz
Close-in SNR: 156 dBc/√Hz, 1 kHz offset, −3 dBFS input
RF digital decimation by 2 and high-pass filter
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
features 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 pseudorandom patterns, and
custom user-defined test patterns entered via the SPI.
APPLICATIONS
Medical imaging/ultrasound
Nondestructive testing (NDT)
Rev. A
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