Department of Information Engineering
University of Pisa
.
Plenary Talk
Advances in Technologies and Architectures for
Low-Power and Highly Integrated Ubiquitous Radars
Prof. Sergio Saponara, PhD
sergio.saponara@iet.unipi.it
2012 IEEE Radar Conference, May 7-11, Atlanta
Outline of the Talk
Scenarios, applications and requirements for
highly-integrated low-power RADAR
RADAR architecture, integration levels, RF/mmWave transceivers and ADC
Ubiquitous low-power RADAR case studies:
E-health (UWB and Doppler)
Automotive (FMCW)
HW-SW implementing platforms for RADAR DSP
Conclusions
2012 IEEE Radar Conference, May 7-11, Atlanta
The electronic components market is
growing, driven by digital-based
highly integrated applications in Sibased tech. addressing societal
needs: health, energy, security,
safety, transport..
Not only nanoscale CMOS (more Moore) but also (more than
Moore) System-in-Package integration of passives, RF & mm-Wave,
high voltage, sensors/actuators (MEMS) ..
World Semiconductor
Statistics
2012 IEEE Radar Source:
Conference,
May 7-11, Trade
Atlanta
Ubiquitous RADAR applications
Pushed by military applications in II world war with high-power, large size
and long-distance systems, today RADAR can be ubiquitous adopted for:
Safer transport systems in automotive, railway, ships …
Bio-signal detection for health care and elderly/infant monitoring
Info-mobility in urban, airport or port scenarios
Civil engineering, (structural health monitoring, landslide monitoring,
ground penetration for detecting pipes, electric lines,….)
Distributed surveillance systems (smart cities, airports, banks, schools)
mm-wave body scanner for security
Environmental monitoring and civil protection
Contactless industrial measurements and in harsh environments
Through-wall target detection
2012 IEEE Radar Conference, May 7-11, Atlanta
Ubiquitous highly-integrated low-power RADAR
RADAR sensing suited to address societal needs (safety, security, health,
transport )  ubiquitous adopted for large volume applications?
RADAR sensing advantages w.r.t. other technologies:
operations in all weather and bad light conditions
contactless sensing and no line of sight sensing
non ionizing radiations
ground penetrating capabilities
multi parameter sensing (target detection, distance, speed, angles)
2012 IEEE Radar Conference, May 7-11, Atlanta
Ubiquitous RADAR design needs
W.r.t. conventional RADARs with large transmitted-power x antenna
aperture product, the realization of highly-integrated RADARs with low
power consumption, size, weight and cost (using standard technologies) is
needed to enable its ubiquitous adoption in large–volume markets
Transmitted Power < 10-15 dBm
Short wavelength for miniaturization (3.9 mm@77 GHz)
Range from < 1m to < 100-200 m
Detection also with low SNR of 10-20 dB
Cross section from tens of cm2 to m2
Pt Gt Gr 2
Pr 
(4 ) 3 R 4
DSP techniques to improve performance and solve range-speed
ambiguities
Receiver sensitivity down to -100 dBm
Multiple channels may be used for channel diversity gain
2012 IEEE Radar Conference, May 7-11, Atlanta
Highly integrated ubiquitous RADAR frequency
At λ of few mm there is potential for high
miniaturization, even the antenna integration
77-81 GHz suited for LRR and SRR,
60 GHz reserved for short range radio
Today, good microwave and mm-Waves
performance for Si-based technologies
2012 IEEE Radar Conference, May 7-11, Atlanta
Outline of the Talk
Scenarios and applications for highly-integrated
low-power RADAR
RADAR architecture, integration levels, RF/mmWave transceivers and ADC
Ubiquitous low-power RADAR case studies:
E-health (UWB and Doppler)
Automotive (FMCW)
HW-SW implementing platforms for RADAR DSP
Conclusions
2012 IEEE Radar Conference, May 7-11, Atlanta
RADAR as mixed analog-digital system
DIGITAL DOMAIN
Control
& Interface
(user or
networking or
mission
processor)
Data
Processing
(adaptive
threshold,
CFAR
detection,
tracking,
classification
..)
Signal
Processing
TX: waveform
gener (DDS), DUC
RX: DDC, beamforming, PCmatch filter, FFT, ..
ADC
DAC
ANALOG
DOMAIN
(PA, LNA, LO,
MIXER, AGC, FILT,
T/R Switch,
Phase Shift)
High peak power in integrated systems problematic  limit on range,
performance gain from DSP rather than power
Integrated high freq T/R (LNA, Mixer, switch, stable LO, ) and embedded
I/F and BB DSP platforms (ADC/DAC + MCU + FPGA/DSP)
2012 IEEE Radar Conference, May 7-11, Atlanta
Low-power RADAR integration levels
System-on-Chip (SoC), System-in-Package (SiP) or Single-board RADAR
SiP is a more viable solution for RADAR than fully SoC
(increased miniaturization entails also increased tech. complexity)
2012 IEEE Radar Conference, May 7-11, Atlanta
Pro/Con of RADAR integration
Pro of Highly Integrated RADAR
Component assembly minimized reducing cost, increasing reliability & lifetime
Small size, small weight, low power consumption
Increased reproducibility and lower cost for large volume production
Con of Highly Integrated RADAR
IC design has high Non Recurring Costs (CAD tools, foundry cost, design time
and team design cost)  cost is minimized only for large volume production
A single technology can not offer
optimal performance for all RADAR
subsystems (CMOS optimal for BB
DSP, not for antenna design or RF PA
or mm-Wave analog design)
Low transmit power limits possible
applications to short range ones
2012 IEEE Radar Conference, May 7-11, Atlanta
RADAR-System-on-a-Board
High transmit power and large aperture antenna RADAR realized
assembling multiple electronic boards, optimized for each subsystem
For low-power ubiquitous RADAR assembling all sub-systems on the
same single printed circuit board (PCB)
-
single chip (few mm2) TX and RX chains at micro or mm-Wave domain and
solid-state power amplifier (CMOS, SiGe, MMIC III-V technologies)
-
ADC/DAC in CMOS tech. IC
-
single chip baseband signal processing
(DSP, FPGA or ASIC) in CMOS
-
memory modules (RAM and NV)
-
Antenna printed on the PCB
Pulsed RADARs can use a single
time-division antenna for TX/RX
FMCW RADARs use separate TX/RX antennas
2012 IEEE Radar Conference, May 7-11, Atlanta
Integrated antennas
Antenna integration trend at board level (printed antenna on PCB),
package level (with LTCC realizing multi-layer circuits with integrated
passives including the antenna), at chip level using MMIC or SoI
At mm-waves (77 GHz RADAR or 60 GHz radio λ is few mm) realizing
an integrated antenna becomes feasible (limited to short-range)
Lot of works still to do to meet RADAR antenna spec (high gain, array
for beam-forming or DOA estimation)  RADAR antennas are off-chip
Single-chip antennas on MMIC or SOI tech. proposed in literature for
60 and 77 GHz (few dB gain)  only for SRR or using special dielectric
lens antenna or smart resonator to improve the characteristics
2012 IEEE Radar Conference, May 7-11, Atlanta
mm-Wave on-chip integrated antenna
Tech
Gain
4 array Dipole
Slot Dipole
Zig zag
F
(GHz)
77
24
24
SiGe
GaAs
CMOS
Ap. Coupled Patch
60
Dipole
Slot Antenna
Cavity backed
folded dipole
Folded Dipole
Yagi
Spiral
Antenna type
Feeder
Imped.
2
2
1.5
BW
(GHz)
2
1.4
N/A
Differential
CPW
N/A
45Ω
50 Ω
30 Ω
CMOS
7
7.8
Balanced
100 Ω
60
60
SiGe
CMOS
2.35
10
7
5
CPS
N/A
30 Ω
N/A
60
SiGe
7
18
CPS
50 Ω
60
60
SiGe
SiGe
8
7
8
9.4
CPW
N/A
100 Ω
50 Ω
60
CMOS SOI
4.2
15
CPW
50 Ω
C. Person,
IEEE BCTM 2010
(J. Hasch et al., IEEE
Tran. Micr Theory Tech, 2012)
2012 IEEE Radar Conference, May 7-11, Atlanta
Competing semiconductor tech. for RADAR
FT
Gain/NF
ratio
Cost
Power
Consumption
Suited for
HBT
High
High
Medium
High
Analog, RF
Si CMOS
Medium
Medium
Low
Low
Digital
High
High
Medium
Medium
Very High
High
High
Medium
SiGe
BiCMOS
III-V
HEMT
Analog, RF,
mixed-signal
mm-wave
2012 IEEE Radar Conference, May 7-11, Atlanta
CMOS technology dominates logic & memory
M. Bhor, IEEE
ISSCC0’9
2012 IEEE Radar Conference, May 7-11, Atlanta
SiGe vs. CMOS vs. III-V technologies
For future, for large volume applications (60 GHz radio, RADAR?) the trend will be
using CMOS also for mm-wave circuits. As an effect of device scaling a Ft higher
than 150 GHz can be obtained
Realizing a mm-wave transceiver in scaled CMOS technology (65 nm or lower), as
baseband DSP, entails a lower area, higher integration and lower cost for large
volume markets but also lower performance vs. 130nm BiCMOS SiGe tech
2012 IEEE Radar Conference, May 7-11, Atlanta
CMOS capability- LNA (Gain & NF)
10
NF, dB - CMOS LNA
Gain, dB - CMOS LNA
25
20
15
8
6
4
2
0
10
1
F (GHz)
10
100
1
F (GHz)
10
State-of-art designs up to 10-20 GHz in CMOS technology have good
performances: gain higher than 20 dB, NF lower than 4 dB
At higher frequencies the performances start decreasing.
Around 77 GHz (W-band) acceptable but non optimal performance are
achieved today (gain lower than 20 dB, NF higher than 4 dB)
2012 IEEE Radar Conference, May 7-11, Atlanta
100
Pout TX, dBm - CMOS PA
CMOS and SiGe capability- PA
35
30
25
20
15
10
5
0
1
10
A. Scavennec et al.,
IEEE Microwave Mag. 2009
F (GHz)
100
1000
2012 IEEE Radar Conference, May 7-11, Atlanta
Migration to SOI for better passive integration
In SOI technology the high resistivity of the substrate on which n- and pMOSFET are created allows dielectric isolation of circuit elements (bulk 20
Ω/cm, SOI > 1000 Ω/cm)
Junction capacitances are reduced increasing maximum operating freq
Reduced noise coupling between digital-analog parts in the same chip
The performances of CPS, CPW or antennas in SOI CMOS are improved
due to a reduced amount of energy loss in the supporting substrate
2012 IEEE Radar Conference, May 7-11, Atlanta
Integrated antenna in CMOS SOI
Incidence of substrate resistivity on achievable radiation efficiency and gain
F. Gianesello,
IEEE SOI 2010
2012 IEEE Radar Conference, May 7-11, Atlanta
ADC – RADAR requirements
ADC operating at IF: sampling rates up to tens, or even hundreds, of MS/s
ADC sampling at several GS/s available but too power hungry and poor bit
resolution  Mixer is needed, full-digital RADAR is not convenient
Multi-channel ADC required (e.g. 4 in last LRR automotive Bosch RADAR)
Bit resolution typically higher than 10 b, e.g. a nominal 14b-16 b required for
12 b-14 b ENOB (70 dB dynamic)
Figure of Merit (FoM) in CMOS tech.
from fJ to pJ per conversion-step
M. Mishali et al. IEEE Signal
Proc. Mag. 2011
2012 IEEE Radar Conference, May 7-11, Atlanta
Outline of the Talk
Scenarios and applications for highly-integrated
low-power RADAR
RADAR architecture, integration levels, RF/mmWave transceivers and ADC
Ubiquitous low-power RADAR case studies:
E-health (UWB and Doppler)
Automotive (FMCW)
HW-SW implementing platforms for RADAR DSP
Conclusions
2012 IEEE Radar Conference, May 7-11, Atlanta
Needs for health monitoring
Due to aging population and needs of national health system cost
reduction there is high interest in monitoring electronic health devices,
specially for heart or respiratory pathologies (CHF, BPCO)
A low-cost RADAR can be used as contactless sensor for monitoring
heart rate or breath rate in patient with cardiopulmonary illness or to
monitors babies while sleeping against sudden infant death syndrome
Acquired RADAR data are then processed by an home gateway an
send to Hospital Information Server
2012 IEEE Radar Conference, May 7-11, Atlanta
Why RADAR for vital signs sensing
A RADAR senses the mechanical activity of heart or chest instead of the
electrical one; from that the heart/breath rate is detected and estimated
The RADAR bio sensor can ensure continuous home monitoring
avoiding wires, gels, LOS requirement, electrodes of conventional
solutions based on SpO2 measures and multi-lead ECG acquisition
(prone to electrode error positioning when done outside hospital )
Sensor RADAR requirements are low-power and high miniaturization
for portability/wearability, short-range, low cost for large volume
market  CMOS silicon integrated approach should be followed
No ionizing effect
2012 IEEE Radar Conference, May 7-11, Atlanta
Which RADAR architecture?
Recent proposals based on Ultra Wide Band pulsed RADAR (within
3-10 GHz range) for very low power and low complex short-range
(tens of cm) contactless vital sign detection
Correlator-type receiver (Zito, De Rossi, Neri, architecture 20072010, implementation in 90 nm CMOS 2011-2012), (Ta-Shun Chu et
al., 130 nm CMOS implementation in 2011)
Doppler RADAR based on transmission of un-modulated signal and
the analysis of the received echo phase modulated by the
chest/heart movement (Dracourt 2004, several works by J. Li, J. Lin
et al.). Various designs at 450 MHz, 1.6 GHz, 2.4 GHz, 5.8 GHz in
various technologies (250 nm CMOS and BiCMOS, 130 nm CMOS,..)
2012 IEEE Radar Conference, May 7-11, Atlanta
UWB pulsed RADAR
Very low power spectral density (-41.3 dBm/MHz from 3.1 to 10 GHz,
14 bands each of 500 MHz) – ETSI/FCC regulation
Robust against interference, no ionization effect
Transceiver activated when needed (low power) narrowband
Narrowband
UWB
noise
2012 IEEE Radar Conference, May 7-11, Atlanta
UWB pulsed RADAR
Due to low power the RADAR is limited to detection of heart/breath
rate of few Hz, at distances of tens of cm
Single TX/RX antenna multiplexed in time
Transmitter: pulse generator in the TX path transmits short pulses, typ
200-400 ps, towards the human body with fPR > 1 MHz so that the
heart can be considered motion-less between consecutive pulses. The
energy level of each pulse amounts to few pJ
Low-complex cross correlation receiver architecture
Zito et al., IEEE TBCS, 2011
2012 IEEE Radar Conference, May 7-11, Atlanta
UWB pulsed RADAR
Output signal modulated by the heart movement (RCS of tens of cm2 )
After a TOF (e.g. few ns for 15-30 cm distance) the signals reflected by the
target is captured by the RX antenna
The signal amplified by the LNA is multiplied with a delayed replica of the
transmitted pulses generated on-chip by a Shaper circuit
The output signal amplitude is related to the heart position. Vital signs vary
within a few Hertz
A 3dB integrator band (Bint) of 100Hz allows an accurate detection
Vo (t) at multiplier output
Vout (t) at integrator output
2012 IEEE Radar Conference, May 7-11, Atlanta
Correlation-type Receiver
Averaging several pulses allows increasing SNR (40 dB, 104 pulses)
SNRimp
f PR
 10  log(
)
Bint
At the low frequency (DC-100 Hz) of the baseband bio-signal the MOS
transistors suffer 1/f flicker noise, higher than thermal noise (KTB term)
NFtot  NF1  ( NF2 1) / G1  ( NF3 1) / G2G1
To have NFtot~NFLNA 20 dB gain required for the LNA if NF2<15 dB  LNA
in 90 nm CMOS: 22.7dB gain, 6dB NF, -19dBm ICP1,<35 mW, <0.7 mm2
Fully differential Gilbert cell mul in
90 nm CMOS with NF 14.3 dB, 12
dB gain, 3.7 mW, 0.3 mm2
2012 IEEE Radar Conference, May 7-11, Atlanta
Transmitter
Pulse generator based on triangular pulse generation (TPG) and shaping
network (SN): two triangular pulsed (delayed by a pulse period) generated
and shaped by a CMOS differential pair
2012 IEEE Radar Conference, May 7-11, Atlanta
Performance of state of art UWB RADARs
fPR in the range 1-10 MHz, pulses of 300-400 ps and 7-8 pJ energy
BB digital processing can be realized with a simple MCU: low-speed
ADC required (12b in ISSCC’11), low data rate serial connection,
mainly control tasks to be implemented
Whole chip by Zito et al. in 90 nm CMOS has <2 mm2 area, < 80 mW
power consumption, 40dB SNR integrator improvement, <1m range
RADAR packaged in QFN32 and mounted on a test-board including
antennas (TX and RX) with 2.3 dBi gain at 3.5 GHz, band 2.8 to 5.4 GHz
covering the range of interest from 3 to 5 GHz.
2012 IEEE Radar Conference, May 7-11, Atlanta
Doppler Bio RADAR
Un-modulated signal transmitted towards the human body, where it is
phase modulated by the physiological movement, then reflected and
captured by the receiver (h and r are heart and respiratory rate)
Using the same TX signal as RX LO signal, the receiver down-converts
the echo signal into BB with no frequency offset. Here it is digitized and
the physiological movement can be identified by DSP (FFT or wavelet)
C. Li et al., IEEE TIM 2010
2012 IEEE Radar Conference, May 7-11, Atlanta
Doppler Bio RADAR
DR at 5.8 GHz (1 GHz bandwidth) realized in 130 nm CMOS technology
powered by 1.5V batteries with direct conversion quadrature receiver
The LNA has 2.56 dB NF and 24 dB gain; the whole RX chain has min 37
dB gain, -32 dBm P1dB, sensitivity of -101 dBm
The system is sized to ensure 10-20 dB SNR, using a baseband
sampling rate of 20 Hz (ADC is sized for 1 kHz)
Off-chip 2x2 patch antennas (separate for TX and RX) were used
With 7 dBm output power detection up to 3 m can be done
C. Li et al., IEEE Tran. Micr. Theory Tech. 2010
2012 IEEE Radar Conference, May 7-11, Atlanta
Automotive RADAR – Why?
Automotive RADARs as core sensor (range, speed) of driver assistance
systems: long range (LRR) for Adaptive Cruise Control, medium range
(MRR) for cross traffic alert and lane change assist, short-range (SRR)
for parking aid, obstacle/pedestrian detection
W.r.t. to other sensing technologies
RADAR is robust in harsh environments
(bad light or weather, extreme temperatures)
Multiple RADAR channels required for
additional angular information
Data fusion in the digital domain with
other on-board sensors
2012 IEEE Radar Conference, May 7-11, Atlanta
Automotive RADAR –a bit of Story
First tentative for mm-wave automotive RADAR since 70’s but
integrated-unfriendly technologies lead to large size, high cost
Since 1998-1999 first generation of RADAR sensors (Daimler, Toyota)
Since 2000 MMIC GaAs-based RADAR in premium cars
Last generation based on 180/130 nm SiGe chipset and advanced
packaging with integrated antenna commercially available (e.g. Bosch)
Radar CMOS transceivers recent announced in 65 nm and 90 nm
High RADAR frequency (small λ) allows small size and weight; highly
integration with SiGe and future CMOS tech. will reduce assembly and
testing costs and hence final user cost much below US$1000
Market expanding at 40%/year and is expected increasing with all
premium/middle cars having a RADAR in next years (7% of all vehicles
sold world-wide, mainly in Europe, Japan and US, will have RADARs)
2012 IEEE Radar Conference, May 7-11, Atlanta
Automotive RADAR – Regulation
24 GHz and 77 GHz are the dominant bands for automotive
77-81 GHz is promising since offers 4 GHz bandwidth
2012 IEEE Radar Conference, May 7-11, Atlanta
Automotive RADAR – 24 vs. 77 GHz
77 GHz is more challenging for designers: given the same technology
the node performances (gain, NF, ..) at 24 GHz are better but 77 GHz
RADARs reduce size, volume, weight and hence cost
77 GHz offers more opportunity for high performance RADAR design:
λ is 3 times smaller (few mm)  smaller antenna size for a given beamwidth spec and/or better angular separability for the same size
Combination of high transmit power and high bandwidth available at 77
GHz for long range operation and fine distance separability
Due to SiGe and CMOS technologies evolution 77 GHz is affordable
77-81 GHz (under regulation worldwide) offers 4 GHz Bandwidth with
EIRP max PSD of - 3dBm/MHz (-9 dBm/MHz outside the vehicle)
2012 IEEE Radar Conference, May 7-11, Atlanta
Automotive RADAR – Technical spec
RCS pedestrian: 0.3 -0.5 mm2, RCS vehicle: 1-20 m2
(J. Hasch et al., IEEE
2012 IEEE Radar Conference,
May
7-11,
Atlanta
Tran. Micr
Theory
Tech,
2012)
Automotive commercial RADARs
(J. Hasch et al., IEEE
Tran. Micr Theory Tech, 2012)
Product size is in the order of 7 cm per side in LRR, 5 cm per side or lower
in MRR and SRR
Products exist with mechanical (slowly, increased size) or electronic beam
forming (increased electronic complexity affordable in new tech nodes)
Multi channel transceivers required
All use FMCW RADAR technique
2012 IEEE Radar Conference, May 7-11, Atlanta
FMCW automotive RADAR principle
f
Target
VCO
Quartz
Osc
fref
Phase
det.
t
Loop
filter
PA
R
Freq. divider
Interface
User I/O
77 GHz
TOF=2R/c
LO
Modulation
control (B, Tm)
X
LNA
RF
f TX
RX
DSP
FFT &
logic
ADC
amp
f fbeat
fbeat
 TOF
t
t
Received signal at the ADC (with up and down chirp , two targets are ambiguous;
with four chirps two targets can be easily resolved)- LFMCW, FSKCW, MFSCW
2012 IEEE Radar Conference, May 7-11, Atlanta
FMCW automotive RADAR equations
Receiver power and SNR (min 10 dB required)
Pt Gt Gr 2
Pr 
(4 ) 3 R 4
fd 
2  vr

Pr
SNR 
K  T  NF  BWFFT
cTcpi ( f   f  )
R

2B
2
c ( f   f )
vR 

2  fc
2
Range and relative speed detection from batiment frequency analysis
(with FFT in digital domain)
The FMCW sweep frequency B and the time sweep determine the
achievable range resolution and speed resolution
2012 IEEE Radar Conference, May 7-11, Atlanta
Automotive RADAR with SiGe mm-Wave T/R
Commercially available from Bosch
based on SiGe Infineon Chipset
2 PCB boards
FCMW modulation
LRR 7dBm Pout, 4 channels (2 TX/RX,
2 RX only), dielectric lens antenna
provides high gain for Rmax 250m
Alternative versions with PCB or onchip Integrated antennas
Power consumption in the order of
Watts
B. Fleming, IEEE Vehicular Tech. Mag. 2012
2012 IEEE Radar Conference, May 7-11, Atlanta
Block diagrams of automotive RADAR with
SiGe mm-Wave T/R
(J. Hasch et al., IEEE
Tran. Micr Theory Tech, 2012)
2012 IEEE Radar Conference, May 7-11, Atlanta
Performance of CMOS transceivers
JSSC2011
JSSC2010
IEEEAESM 2012
65 nm
CMOS
90nm
CMOS
guidelines for CMOS
243 mW
517 mw
N/A
1 mm2
6.8 mm2
N/A
Carrier frequency
77 GHz
77 GHz
77 GHz
Resolution
20 cm
N/A
< 1m
Doppler resolution
5 km/h
N/A
~5 km/h
Range and
antenna gain
106 m with
off-chip 24 dB
antenna
10 m with
off-chip 20 dB
antenna
>100m with off-chip 24
dB antenna,
<10 m with on-chip 4 dB
antenna
On-chip PA output
5 dBm
-2.8 dBm
<10 dBm
Technology
Power
consumption
Area
RX gain
LNA+mixer+IF
Sweep time Tm
1.5 ms
23 dB
LNA+mixer
0.5 ms
Sweep freq. B
700 MHz
614 MHz
FFT points
2048, 3 MS/s
4096, 2 MS/s
~38.7 dB
~40 dB
~1 ms
150-750 MHz
up to 8192, few MS/s
Today SiGe-based RADAR T/R for commercial automotive RADAR
Tomorrow CMOS-based expected (given technology evolution and trends
towards more digital systems)
2012 IEEE Radar Conference, May 7-11, Atlanta
Single and multi beam-forming
Analog beam-forming
Digital beam-forming
To form a beam in a direction, each
element of the array is followed by a time
delay (phase shifters for narrow band)
when all the outputs are summed they add
up coherently to form a beam
Figures from Skolnik book
Analog/digital
2012 IEEE Radar Conference, Maybeam-forming
7-11, Atlanta
DOA estimation - Monopulse
H. Rohling, Automotive Radar tutorial, 2008
It needs two beams for
each angular coordinate
Sum  and difference Δ
patterns are used
Normalized antenna pattern
1
0.5
0
Example, with Gaussian
antenna pattern and
-3dB beam-width=3o
-0.5


-1
-8
-6
-4
-2
0
2
azimuth  (degrees)
4
6
8
2012 IEEE Radar Conference, May 7-11, Atlanta
Outline of the Talk
Scenarios and applications for highly-integrated
low-power RADAR
RADAR architecture, integration levels, RF/mmWave transceivers and ADC
Ubiquitous low-power RADAR case studies:
E-health (UWB and Doppler)
Automotive (FMCW)
HW-SW implementing platforms for RADAR DSP
Conclusions
2012 IEEE Radar Conference, May 7-11, Atlanta
Implementing platforms for RADAR DSP
Ubiquitous integrated RADAR applications (automotive, bio,..) needs lowpower consumption (reduced power supply and thermal issues and
increased portability) but can require high computational capabilities and
large data transfer rate and memory storage size
Energy-flexibility trade-off to be found between SW-oriented (GPP, DSP,
GPU, Microcontroller) and HW-oriented (ASIC, FPGA) platforms
R. Whil, IWPC 2011
2012 IEEE Radar Conference, May 7-11, Atlanta
Custom SoC or MCU for RADAR
RADAR is not yet a commodity with accepted/frozen standards
Custom SoC design can provide the best in terms of performance
(analog/RF/digital) for a given technology at minimum area and power occupation.
Flexibility can be achieved adding in the ASIC also programmable cores
ASIC development time and costs are high  rather than designing custom SoC for
RADAR in next years an architecture based on MCU+ (DSP/FPGA) is more suited
Thanks to the availability of IP cores such designs can be seen also a prototyping
step towards a migration to SoC if and when RADAR becomes a commodity
MCU has low-cost & low-power, on-chip ADC/DAC, but low-performance
capabilities (MIPS rather than GOPS, integer operations, low data–rate digital I/O)
For RADAR, MCU suitable for applications needing control of data/operation flow
but a co-coprocessor is needed for DSP
2012 IEEE Radar Conference, May 7-11, Atlanta
Why not General Purpose Processors (GPP)?
GPP are evolving as SW-programmable computing architecture with
many cores, large operand size (64b or higher), tens of GOPS, multiple
cache levels (several Mbytes on chip) and fast connections to off-chip
DDR memories or networks
However the energy efficiency (<<1GFLOPS/Watt) and absolute power
(tens of Watts) are far from specs of highly-integrated low-power RADAR
applications
Intel I5 multicore example
2012 IEEE Radar Conference, May 7-11, Atlanta
Digital Signal Processors
SW-programmable with instruction set optimized for DSP (e.g. ALU with HW
resources for fast MAC, fixed or floating point versions available)
Different architectural approaches: SIMD, VLIW up to GPU (TFLOPS performance
higher than multi-core GPP and with better energy efficiency for DSP tasks)
DSP for consumer, automotive and biomedical markets already available
DSP available also as IP cores (soft or hard macro) to be integrated in custom IC
2012 IEEE Radar Conference, May 7-11, Atlanta
GPU vs GPP
Comparison of computational and bandwidth capabilities and power cost
of some GPP and GPUs
2012 IEEE Radar Conference, May 7-11, Atlanta
GPU vs GPP
NVIDIA GTX260 GPU tested against Core2Duo GPP E8x series for several RADAR
DSP classic algorithms
GPU has a speed-up from 10% up to two orders of magnitude vs. GPP depending:
the algorithms, the size of the input array data, the regularity and parallelization
degree of the data flow, the bottleneck caused by memory transfers
Large speed-up for filters
Smaller speed-up for CFAR
The GPU kernel is faster than
the GPU computing platform
considering also memory system
Patterson et
SAAB 2010
al,
2012 IEEE Radar Conference, May 7-11, Atlanta
FPGA (Field Programmable Gate array)
FPGAs are evolving from reconfigurable HW devices to complex Systems
on Programmable Chip (SoPC) with: integrated reconfigurable logic
blocks (FF, LUT) and I/O blocks, memory blocks, DSP-units (Mult Add,)
soft/hard SW cores (Microblaze, Nios, ARM Cortex,..)
Different FPGA technologies exist: Flash (ProAsic), Anti-fuse (AX, RTAX) ,
SRAM (Virtex, Spartan, Cyclone, Stratix) some already qualified for
automotive or even space/military applications
For DSP intensive applications SRAM-based are typically preferred
Mixed-signal FPGAs also exist(Fusion)
FPGA designs for DSP require algorithmic
and HW know-how: HDL and synthesis tools
2012 IEEE Radar Conference, May 7-11, Atlanta
High-end FPGA for RADAR DSP
High-end FPGAs for intensive RADAR DSP are available but cost (>1000
USD) and power consumption are too high for ubiquitous low-power apps
Virtex6 LX760 FPGA in 40 nm for FFT
processing has 380 GFLOPS at 50 W
Stratix Altera FPGA in 28 nm with
variable precision DSP blocks, 2 TMACs
Efficiency (GFLOPS/W, GFLOPS/mm2):
- FPGA worse vs. Custom IC
(1 order of magnitude)
- better performance by 1 order of
magnitude vs. GPP
- slightly better than GPU (GTX480)
2012 IEEE Radar Conference, May
7-11,
E. Chung,
IEEEAtlanta
Micro 2010
Cost-effective FPGA for RADAR DSP
To fit the DSP RADAR requirements of low-cost low-power applications
the challenge is an optimized algorithmic-architecture co-design on less
complex FPGA families with HW-SW capabilities
MCU+DSP functionalities of a FMCW automotive RADAR realized in Xilinx
Virtex2Pro (Microblaze + radix-2 FFT processor 2048-point, 14 b)
Control and DSP tasks of a 77 GHz FMCW RADAR with GaAs MMIC frontend and MEMS switch realized in Spartan-3A and Virtex-5 SX50T (switch
control, TX sweep gen, Hamming filtering, FFT, CFAR, peak pairing)
11b ADC, 10b DAC, 12b/16b
DSP data/coefficient resolution
S. Lal, IEEE RSP 2011
2012 IEEE Radar Conference, May 7-11, Atlanta
Cost-effective FPGA for RADAR DSP
Virtex5 SX50T: 8160 slices (4 LUT+4FF), 5000 kb RAM; 288 DSP48 unit
(25x18 mul+acc +adder), 12 DCM 6 PLL, fast I/O
Spartan3 A-DSP (XA3SD1800A): 16640 slices (2LUT+2FF), 1500 kb RAM,
84 18x18 mul, 8 DCM, automotive grade device exist
S. Lal, IEEE RSP 2011
2012 IEEE Radar Conference, May 7-11, Atlanta
Conclusions
RADAR sensing suited to address societal needs of safety, security, healthcare, intelligent transport with big advantages vs. other technologies
Differently from high power and large antenna RADARs, highly-integrated
systems with low power consumption, size, and cost are needed for the
ubiquitous adoption of RADARs in large–volume markets
Opportunities for miniaturization at mm-waves (λ of few mm)
Key enabling factor is the realization, in Si-based CMOS or BiCMOS tech.,
of integrated transceivers for the RADAR front-end with enough NF, gain
and power to meet automotive or bio RADAR requirements
The path to full CMOS/CMOS SOI to be completed as well as advanced
concepts for System-in-Package integration to be further explored
2012 IEEE Radar Conference, May 7-11, Atlanta
Conclusions
ADC at IF and increasing RADAR signal processing in the digital
domain (FFT, filtering, pulse comp., beam-forming, CFAR, tracking), with
cost-effective embedded platforms (MCU+FPGA), allows for high
performance RADAR in standard tech. at low power and low size
Proof-of-concept demonstrators of ubiquitous low-power RADAR and
first commercial solutions recently available for UWB pulsed RADAR for
bio and FMCW automotive RADAR (LRR, MRR and SRR)
RADAR advances also at system and algorithmic level:
- Sensor fusion of RADAR systems with other sensor technologies
- Networks of small RADARs used to improve the performance in terms
of angular, speed, range accuracy and number of tracked targets
- In networked RADAR scenario new DSP functions to be adopted (e.g.
code division multiple access to avoid crowding, MIMO techniques)
2012 IEEE Radar Conference, May 7-11, Atlanta
Thanks for your attention
Acknowledgment
Discussions with
Bruno Neri, Full Professor of RF electronics
and
Maria S. Greco, Associate Professor of Telecommunications
at University of Pisa
are gratefully acknowledged
2012 IEEE Radar Conference, May 7-11, Atlanta