Octal Ultrasound AFE
with Digital Demodulator
AD9670
Data Sheet
FEATURES
GENERAL DESCRIPTION
8 channels of LNA, VGA, antialiasing filter, ADC, and digital
demodulator/decimator
Low power
The AD9670 is designed for low cost, low power, small size, and
ease of use for medical ultrasound applications. It contains eight
channels of a VGA with an LNA, a CW harmonic rejection I/Q
demodulator with programmable phase rotation, an antialiasing
filter, an ADC, and a digital demodulator and decimator for data
processing and bandwidth reduction.
150 mW per channel, time gain compensation (TGC) mode,
40 MSPS
62.5 mW per channel, continuous wave (CW) mode;
<30 mW in power-down mode
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.
10 mm × 10 mm, 144-ball CSP_BGA
TGC channel, input referred noise voltage: 0.82 nV/√Hz,
maximum gain
Flexible power-down modes
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.
Fast recovery from low power standby mode: <2 μs
Low noise preamplifier (LNA)
Input noise voltage: 0.78 nV/√Hz, gain = 21.6 dB
Programmable gain: 15.6 dB/17.9 dB/21.6 dB
0.1 dB input compression point: 1.00 V p-p/0.75 V p-p/
0.45 V p-p
Flexible active input impedance matching
Variable gain amplifier (VGA)
Attenuator range: 45 dB, linear-in-dB gain control
Postamplifier gain (PGA): 21 dB/24 dB/27 dB/30 dB
Antialiasing filter
Programmable, second-order low-pass filter from 8 MHz to
18 MHz or 13.5 MHz to 30 MHz and high-pass filter
Analog-to-digital converter (ADC)
Signal-to-noise ratio (SNR): 75 dB, 14 bits up to 125 MSPS
Configurable serial low voltage differential signaling (LVDS)
CW 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
Digital demodulator/decimator
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, antialiasing filter, 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
pseudorandom patterns, and custom user-defined test patterns
entered via the SPI.
I/Q demodulator with programmable oscillator FIR
decimation filter
APPLICATIONS
Medical imaging/ultrasound
Nondestructive testing (NDT)
Rev. A
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