AD9271 Datasheet, PDF (1/58 Pages) Analog Devices – Octal LNA/VGA/AAF/ADC and Crosspoint Switch

Preliminary Technical Data
FEATURES
8 channels of LNA, VGA, AAF, and ADC
Low noise preamplifier (LNA)
Input-referred noise = 1.2 nV/√Hz @ 7.5 MHz typical
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 match
Bandwidth (BW) > 70 MHz
Full-scale (FS) output = 2 V p-p diff
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/channel at 12 bits/40 MSPS (TGC)
60 mW/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-pin 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 amplifier
(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
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,
FUNCTIONAL BLOCK DIAGRAM
LOSW-A
LO-A
LI-A
LG-A
LOSW-B
LO-B
LI-B
LG-B
LOSW-C
LO-C
LI-C
LG-C
LOSW-D
LO-D
LI-D
LG-D
LOSW-E
LO-E
LI-E
LG-E
LOSW-F
LO-F
LI-F
LG-F
LOSW-G
LO-G
LI-G
LG-G
LO-H
LOSW-H
LI-H
LG-H
LNA
VGA
LNA
VGA
LNA
VGA
LNA
VGA
LNA
VGA
LNA
VGA
LNA
VGA
LNA
VGA
g_m
6
SWITCH
ARRAY
AAF
AAF
AAF
AAF
AAF
AAF
AAF
AAF
AD9271
12-BIT
PIPELINE
ADC
SERIAL
LVDS
12-BIT
PIPELINE
ADC
SERIAL
LVDS
12-BIT
PIPELINE
ADC
SERIAL
LVDS
12-BIT
PIPELINE
ADC
SERIAL
LVDS
12-BIT
PIPELINE
ADC
SERIAL
LVDS
12-BIT
PIPELINE
ADC
SERIAL
LVDS
12-BIT
PIPELINE
ADC
SERIAL
LVDS
12-BIT
PIPELINE
ADC
SERIAL
LVDS
REFERENCE
DOUT + A
DOUT – A
DOUT + B
DOUT – B
DOUT + C
DOUT – C
DOUT + D
DOUT – D
DOUT + E
DOUT – E
DOUT + F
DOUT – F
DOUT + G
DOUT – G
DOUT + H
DOUT – H
FCO+
FCO–
DCO+
DCO–
Figure 1.Block Diagram
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. PrA
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