Autonomous Cars:Radar, Lidar, Stereo Cameras
1 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
CAMERAS FOR AUTONOMOUS DRIVING
2 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Role of Cameras in Automotives
Camera module market ~$25B in 2015, expected to double by 2025 (Yole)Machine Vision integration with multiple sensors for ADAS and partial autonomous drivingDisadvantages of cameras• Environmental conditions can introduce problems• Difficulty in detecting non- illuminated and varying lighting conditions• Computer vision limitations for reliable detection
3 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
CMOS image sensors for Automotive are quite different from Consumer Electronics
Source: Yole
Improved Low light sensitivity by larger pixel sizeLower resolution (it’s not about Mega pixels)Fast response time (significantly faster than smartphone cameras
Packaging Differences• Embedded logic in image sensor package• Ceramic packages for higher functional safety requirements
4 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
ChallengesFast image acquisitionStereo camera for depth and distance of the object in image planeHigh resolution AND high speed
• Resolution: greater than 1k x 1k pixels, aim for 4k x 4k• Frame rate: 60 fps and higher for shorter reaction time
Zoom into image area for a greater detail Efficient image processing for real-time analysisWider field of view than radar or laser systems
5 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Cameras in Current Cars (Bosch)
Bosch‘s mono and stereo camera system: smallest currently available in the market. Has a 50-degree horizontal field of view for 50m distance.
Bosch’s stereo camera system
6 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Cameras in Current Cars (Panasonic)
Stacked CMOS imaging chip and processing electronics in one packageCompact enough to fit within rearview mirror assembly or behind the windshieldLow cost high resolution cameras, but limited speedHigh speed cameras limited resolutionCircuits for efficient image processing for real-time analysisCan be implemented with multiple units for stereo vision
Panasonic CMOS 34227 Sensor
7 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Prior Work at GT: 1st CIS DEMONSTRATOR on LOW COST 3D GLASS PACKAGE
100um Thin Glass Substrate
Wafer Level Camera on Top Side
Thin Logic Emulator IC on bottom side
Solder reflow at chip level
Passed initial tests at Georgia Tech
8 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Thermal Control Using Glass PackageGlass limits lateral thermal spreading by designJunction temperatures can be reduced by vertical copper viasHeating of image sensor with IC stacking or silicon interposers
Without copper With copper
Glass
38C 58C 48C 50C
49.1C 49.4C 49.1C 49.4C
Silicon10mm x 10mm Test Chipon Glass or Si Interposer
9 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
RADAR
10 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Why RADAR in NAE?
• Above functions Require radar sensors due to their robustness in varying environmental conditions like rain, dust, or sunlight
(J. Hasch, "Driving towards 2020: Automotive radar technology trends," Microwaves for Intelligent Mobility (ICMIM), 2015 IEEE MTT-S International Conference on, Heidelberg, 2015, pp. 1-4.)
Roadmap for driver assistance functions
• Short, Medium and Long Range RADAR Modules
Critical to Fully Autonomous Driving
11IEEE-CPMT Workshop – Autonomous Cars
Automotive RADAR – Brief Intro
• Basic Architecture and Requirements- Frequency Modulated Continuous Wave (FMCW) Doppler Radar- 76 GHz – 81 GHz- Severe Environment Conditions- Long Term Reliability
Many challenges to device and design !!
TxRx
fr
Freq
uenc
y
fb
fd
fb fd
fr
Transmit FMCW Signal76-81 GHz
Compare Received Signal with Transmitted Signal to Extract
Distance and Velocity
PROF. JOHN CRESSLER
12 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Automotive RADAR Evolution
1999 Mercedes-Benz • First manufacturer to use radar
for autonomous cruise control (ACC) system in S-class
Active Components Evolution
Pack
agin
g Ev
olut
ion
GaAs Technology
• Discrete semiconductor components MMIC blocks or even complete
transceiver circuits
Silicon-based SiGe technology• Improved RF performance at high freq.• Destined to be the mainstream
semiconductor technology millimeter-wave
(J. Hasch, E. Topak, R. Schnabel, T. Zwick, R. Weigel and C. Waldschmidt, "Millimeter-Wave Technology for Automotive Radar Sensors in the 77 GHz Frequency Band," in IEEE Transactions on Microwave Theory and Techniques, vol. 60, no. 3, pp. 845-860, March 2012.)
Chip on board wire bonding
Flip chip mounting on substrate
eWLB (embedded wafer level
BGA) package
Evolution of SiGe Device Technology
Courtesy of P. Chevalier
13 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Challenges in Automotive RADARPackage Challenges
Low losses and reflections chip to substrateTransitionThermal dissipationHigh Reliability
Low cost
• Generation of sufficient output power at high frequency
• LNA demonstration
Device Challenges
• No LNA: High NF → Low SNR → Lowmaximum detecting range of system
77GHz 4-channel automotive radar transceiver chip specification
(H. P. Forstner et al., "A 77GHz 4-channel automotive radar transceiver in SiGe," Radio Frequency Integrated Circuits Symposium, 2008. RFIC 2008. IEEE, Atlanta, GA, 2008, pp. 233-236. )
14 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Status of Automotive RADAR Products
Bosch LRR3 Sensor• SiGe MMICs instead of Gunn oscillators and discrete mixer diodes • Size and package complexity reduction
Bosch LRR3 SensorBosch LRR2 Sensor
15 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Latest Automotive RADAR Products
Bosch Mid Range Radar (MRR) Sensor• Frequency band 76-77 GHz• Distance range up to 160 meters • Integrates two electronic boards and STMicroelectronics devices• RF board with Hybrid PTFE/FR4 substrate and equipped with planar antennas• Infineon 77GHZ SiGe Monolithic Microwave Integrated Circuits (MMIC) used as High-Freqency
transmitter and receiver
16 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Recent Automotive RADAR Packaging Technologies Infineon RRN7745P & RTN7735P eWLB Fan-out Package - 77GHz Radar Dies
The radar receiver die is packaged in an eWLB (embeddedWafer Level BGA) package, Fan-Out technology fromInfineon.
Back view
Die3mm x 3mm
Package cross-section
17IEEE-CPMT Workshop – Autonomous Cars
Proposed High Linearity Low Noise RX
Block Diagram
One of the first Radar modules to integrate LNA in front endLeading Edge SiGe Receiver
Employ Advanced SiGe Node
Use Novel Circuit Design
Incorporate High Gain High Linearity
LNA
Current Design Phase
LNA layout modificationPROF. JOHN CRESSLER
18IEEE-CPMT Workshop – Autonomous Cars
Proposed High-Linearity LNA
IBM 9HP 90nm technology3 cascaded cascode stagesFully differential to improve CMRRInput transformer balun:
- Provide RF ESD protection and differential signal
Inter-stage matching with transformersVariable gain
- Improve input P1dB
Area: 0.6mm x 1 mmVCC: 2.5V
IN
OUT
VCC
VB1_13
VB2_13
VB1_2
VB2_2
GND
GND
GND
PROF. JOHN CRESSLER
19IEEE-CPMT Workshop – Autonomous Cars
LNA Initial Design and SimulationTransistor Sizing: 6um, 8um, 10um Simulation Results
S-param
NF
P1dB
Gain 17.3 dBNF 6.221 dB3dB Freq 56GHz-94GHzDC Power 91.5 mWInput P1dB -14.5 dBm
PROF. JOHN CRESSLER
IEEE-CPMT Workshop – Autonomous CarsSlide 20
CONFIDENTIAL
GT Program FocusThe research objective is to design and demonstrate an ultra miniaturized low costintegrated 77GHz radar & high speed camera module applying the most advancedpanel-level glass fan-out (PGFO) packaging technologies to the following parameters:
77 GHz Radar Chip
Processor
Image sensor
Antenna Incident light
Glass
Cover glass
Active area Camera ModuleRadar Module
Properties Objectives Prior Art
Integrated Module
Package type GFO FO-WLP/ CeramicCost 500 um
RadarNoise Figure 6-7 dB > 20 dB
Gain 15 dB < 15 dBAntennas Integrated in package Integrated in PCB
CameraData Rate ~ 1 Gbps 1 ms
21 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
LIDAR
22 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Why Lidar for Automotive ?
Cameras and radar cannot ensure 100 % safetyRadars provide no object detectionCameras depend on environmental conditions.Lidar enables high precision detection in real time Time of Flight lasers in Lidar are the most accurate for real time and long range detection.
23 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Basics of Lidar
Fired Laser Pulses
Reflected Laser Pulses
Starting a timer when the pulse goes out and stopping by the reflected pulse
24 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Challenges
Cost reduction (see figure)Miniaturization for easy integration in car bodyHigh aperture angle – number of channels Reliability by application of solid state lidar
25 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Lidar Products
Velodyne lidar system VLP-16• Range: 100 m, • Power consumption: ~8 W, • Weight: 830 grams, • Footprint:~Ø103 mm x 72 mm,• 16 channels, ~300,000
points/sec, • 360° horizontal field of view,
30° vertical field• Accuracy: +/- 3 cm (typical)• Rotating mirror inside
assembly,• Laser: Class 1 – 903 nm
wavelength
26 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Lidar Products
Quanergy Solid-state LIDAR system• Field of view is 120 degrees both horizontally and vertically. • The minimum range is 10 cm, and the maximum range is at least
150 m at 8 percent reflectivity. • At 100 meters, the distance accuracy is +/- 5 cm, and the
minimum spot size is just 9 cm.
Small (9 cm x 6 cm x 6 cm), no moving parts
27 | IEEE-CPMT Workshop – Autonomous Cars Prof. Rao R. Tummala
Solid State Lidar
Uses an optical phased array as a transmitter (no micro mirrors), which steers laser pulses by shifting the phase.
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