AD9279 Datasheet, PDF (1/44 Pages) Analog Devices – Octal LNA/VGA/AAF/ADC and CW I/Q Demodulator

Octal LNA/VGA/AAF/ADC
and CW I/Q Demodulator
AD9279
FEATURES
8 channels of LNA, VGA, AAF, ADC, and I/Q demodulator
Low power: 141 mW per channel, TGC mode, 40 MSPS;
60 mW per channel, CW mode
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: 0.75 nV/√Hz, gain = 21.3 dB
Programmable gain: 15.6 dB/17.9 dB/21.3 dB
0.1 dB compression: 1000 mV p-p/
750 mV p-p/450 mV p-p
Dual-mode active input impedance matching
Bandwidth (BW): >100 MHz
Variable gain amplifier (VGA)
Attenuator range: −45 dB to 0 dB
Postamp gain (PGA): 21 dB/24 dB/27 dB/30 dB
Linear-in-dB gain control
Antialiasing filter (AAF)
Programmable second-order LPF from 8 MHz to 18 MHz
Programmable HPF
Analog-to-digital converter (ADC)
SNR: 70 dB, 12 bits up to 80 MSPS
Serial LVDS (ANSI-644, low power/reduced signal)
CW mode I/Q demodulator
Individual programmable phase rotation
Output dynamic range per channel: >160 dBc/√Hz
Output-referred SNR: 155 dBc/√Hz, 1 kHz offset, −3 dBFS
GENERAL DESCRIPTION
The AD9279 is designed for low cost, low power, small size,
and ease of use for medical ultrasound and automotive radar. It
contains eight channels of a variable gain amplifier (VGA) with
a low noise preamplifier (LNA), an antialiasing filter (AAF), an
analog-to-digital converter (ADC), and an I/Q demodulator
with programmable phase rotation.
Each channel features a variable gain range of 45 dB, a fully
differential signal path, an active input preamplifier termination,
and a maximum gain of up to 52 dB. 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 21.3 dB LNA gain, the LNA input SNR is roughly 94 dB.
In CW Doppler mode, each LNA output drives an I/Q demod-
ulator 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.
FUNCTIONAL BLOCK DIAGRAM
AVDD1 AVDD2
PDWN STBY
DRVDD
LO-A TO LO-H
LOSW-A TO LOSW-H
LI-A TO LI-H
LG-A TO LG-H
LNA
I/Q
DEMODULATOR
VGA
AAF
8 CHANNELS
12-BIT
ADC
SERIAL
LVDS
DOUTA+ TO DOUTH+
DOUTA– TO DOUTH–
LO
GENERATION
REFERENCE
SERIAL
PORT
INTERFACE
DATA
RATE
MULTIPLIER
FCO+
FCO–
DCO+
DCO–
Figure 1.
Rev. 0
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