AD9271_15 Datasheet, PDF (1/60 Pages) Analog Devices – Octal LNA/VGA/AAF/ADC and Crosspoint Switch

FEATURES
8 channels of LNA, VGA, AAF, and ADC
Low noise preamplifier (LNA)
Input-referred noise = 1.1 nV/√Hz @ 5 MHz typical,
gain = 18 dB
SPI-programmable gain = 14 dB/15.6 dB/18 dB
Single-ended input; VIN maximum = 400 mV p-p/
333 mV p-p/250 mV p-p
Dual-mode active input impedance matching
Bandwidth (BW) > 70 MHz
Full-scale (FS) output = 2 V p-p differential
Variable gain amplifier (VGA)
Gain range = −6 dB to +24 dB
Linear-in-dB gain control
Antialiasing filter (AAF)
3^rd-order Butterworth cutoff
Programmable from 8 MHz to 18 MHz
Analog-to-digital converter (ADC)
12 bits at 10 MSPS to 50 MSPS
SNR = 70 dB
SFDR = 80 dB
Serial LVDS (ANSI-644, IEEE 1596.3 reduced range link)
Data and frame clock outputs
Includes crosspoint switch to support
continuous wave (CW) Doppler
Low power, 150 mW per channel at 12 bits/40 MSPS (TGC)
90 mW per channel in CW Doppler
Single 1.8 V supply (3.3 V supply for CW Doppler output bias)
Flexible power-down modes
Overload recovery in <10 ns
Fast recovery from low power standby mode, <2 μs
100-lead TQFP
APPLICATIONS
Medical imaging/ultrasound
Automotive radar
GENERAL DESCRIPTION
The AD9271 is designed for low cost, low power, small size,
and ease of use. It contains eight channels of a variable gain amp-
lifier (VGA) with low noise preamplifier (LNA); an antialiasing
filter (AAF); and a 12-bit, 10 MSPS to 50 MSPS analog-to-digital
converter (ADC).
Each channel features a variable gain range of 30 dB, a fully
differential signal path, an active input preamplifier termination, a
maximum gain of up to 40 dB, and an ADC with a conversion
rate of up to 50 MSPS. The channel is optimized for dynamic
performance and low power in applications where a small
package size is critical.
Octal LNA/VGA/AAF/ADC
and Crosspoint Switch
AD9271
FUNCTIONAL BLOCK DIAGRAM
LOSW-A
LO-A
LI-A
LNA
VGA
LG-A
LOSW-B
LO-B
LI-B
LG-B
LNA
VGA
LOSW-C
LO-C
LI-C
LG-C
LNA
VGA
LOSW-D
LO-D
LI-D
LNA
VGA
LG-D
LOSW-E
LO-E
LI-E
LG-E
LNA
VGA
LOSW-F
LO-F
LI-F
LG-F
LNA
VGA
LOSW-G
LO-G
LI-G
LNA
VGA
LG-G
LOSW-H
LO-H
LI-H
LG-H
LNA
VGA
SWITCH
ARRAY
AD9271
AAF
12-BIT
ADC
SERIAL
LVDS
DOUTA+
DOUTA–
AAF
12-BIT
ADC
SERIAL
LVDS
DOUTB+
DOUTB–
AAF
12-BIT
ADC
SERIAL
LVDS
DOUTC+
DOUTC–
AAF
12-BIT
ADC
SERIAL
LVDS
DOUTD+
DOUTD–
AAF
12-BIT
ADC
SERIAL
LVDS
DOUTE+
DOUTE–
AAF
12-BIT
ADC
SERIAL
LVDS
DOUTF+
DOUTF–
AAF
12-BIT
ADC
SERIAL
LVDS
DOUTG+
DOUTG–
AAF
12-BIT
ADC
REFERENCE
SERIAL
LVDS
DOUTH+
DOUTH–
FCO+
FCO–
DCO+
DCO–
Figure 1.
The LNA has a single-ended-to-differential gain that is selectable
through the SPI. The LNA input noise is typically 1.2 nV/√Hz,
and the combined input-referred noise of the entire channel
is 1.4 nV/√Hz at maximum gain. Assuming a 15 MHz noise
bandwidth (NBW) and a 15.6 dB LNA gain, the input SNR is
roughly 86 dB. In CW Doppler mode, the LNA output drives a
transconductance amp that is switched through an 8 × 6
differential crosspoint switch. The switch is programmable
through the SPI.
Rev. B
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