Using a Test-Cell-Solution Approach to Achieve Device Quality and Production-Efficiency Goals for 77GHz Automotive Radar MMICs

Why do we need Automotive Radar?

http://floridabicycle.org/

http://www.motortrend.com

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Why do we need Automotive Radar?

• General trend towards safer, more autonomous vehicles

• Legislation to reduce car injuries is causing four-fold growth in ADAS (Advanced Driver Assistance Systems) chip revenue from 2010 - 2020

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Automotive Radar Applications

Application Detection Range Safety Aspect Technology

Adaptive Cruise Control 200 meters Normal driving; accident

avoidance 77 GHz Radar

Pre-Crash 30 meters Accident; mitigation of

impact

77 GHz Radar / 24 GHz

Radar 76 / 81 GHz Radar

Blind Spot Detection 20 meters Normal driving; accident

avoidance

24 GHz Radar/ Vision

sensor

Lane Departure Warning 60 meters Normal driving; accident

avoidance Vision sensor

Stop and Go 30 meters Normal driving; accident

avoidance

77 GHz + 24 GHz Radar

76/81 GHz Radar

• ADAS uses multiple technologies including Radar-based systems

• Radar applications are moving from 24GHz to 77GHz, improving range, bandwidth and resolution for detecting objects

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Push to Higher Bandwidth – 79GHz 5 GHz 200MHz

Source: ITU News

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The Test Challenge for Automotive Radar

• “Sub ppm” failure rates full functional test required

• Reliable and cost-effective HVM solution

• Maximize re-use of test cell investment

• Multi-temp testing from -55 to +150°C

Source: CVEL Automotive Electronics 6

Automotive Radar Integrated Test Cell

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• High volume production “at speed“ testing solution for ADAS Radar enabled devices

− Automotive compliant Tri-temp testing and handling

− Commercial ATE and handler platform , with optional 24GHz or 77GHz Tx and Rx

− Fully-matched contactor and interfacing assembly

• Lowest number of signal transitions provides better signal integrity

• Packaged device and WLCSP compliant

− Mechanical interfacing and integrated test cell communication

Tri-Temp Handler General Purpose ATE

Integrated 77GHz test and

contactor assembly

Optimized transmission paths

Starting point – 24GHz RF Test

• A co-development between ST and Xcerra has already implemented 24GHz functional test to maintain the highest device quality levels

• Uses flexible test cell base that can be adapted for other requirements

• Signal interfaces have been designed for optimal system-level electrical and thermal performance

• The test cell base is now being extended with new HS instrumentation and interfaces to provide a 77GHz functional test solution in collaboration with ST.

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24GHz Test Cell Signal I/F Optimization • Complete signal path optimized between DUT and ATE through design, simulation

and measurement

– Less than 8dB of loss (23-26.5GHz)

– Less than 2dB of ripple in passband (23-26.5GHz)

– Die temp. accuracy of ±2°C (die temperature) at cold test while maintaining the stringent RF requirements

• Custom insulation on tester-side of loadboard PCB and contactor design enables shorter signal-lengths and more stable multi-temp performance

• Air flow for multi-temp support integrated with handler kit

Insulation on back of

Loadboard

Temperature Drift

Te

mp

(°C

)

-44

-40

-36

-32

-28

-24

-20

-16

0 20 40 60 80 100

time (s)

2°C

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Elements of the 77GHz Test Cell

Contact Unit Holder

and Multi-Temp

Insulation

Tester-Handler

Docking

Loadboard and

Contactor Interface

77GHz RF Test Option

Scalable SOC

ATE System

Tri-Temp

P&P Handler

Multi-Axis TH

Manipulator

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Optimized Tester-

Handler Communication

Key Test Technology in 77GHz Radar Test Cell

• 77GHZ Integrated contactor, adaptor & interface board

– Designed to ensure shortest possible path from 77GHz instrument to DUT

– Validated over automotive test temperature ranges

• Tri-temp (-55°C to +175°C ), Automotive-compliant Pick and Place handler and validated docking

• 77GHz Automotive Radar test option

– Configured as upgrade on scalable ATE platform to balance flexibility and cost

• Calibration of RF to device pin or ball

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Signal Path Optimization for 77GHz

• Integrated design and simulation of the complete signal path

• Minimizes connection interfaces and maintains required 77GHz signal quality and robustness for production

• Measurements confirm simulation results: -10dB return loss @ 81GHz

RF Instrument <-> Loadboard <-> Contactor <-> DUT

Integrated interface design

reduces signal transitions

by 3X

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ST 77GHz Radar Chipset Integration

Source: STMicroelectronics

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Key Features of the ST 77GHz MMIC

• The monolithic MMIC/DUT has 38GHz LO and 3x Tx + 4 x Rx 77GHz channels to implement multiple beams solution.

• The device also includes high speed ADCs and serializers, enabling >600Mbit/s serial I/O to allow high speed data transfer

• In package solution for improved application performance, better and cheaper manufacturing flow at OEMs

Source: STATSChipPAC

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Source: STMicroelectronics

Xcerra 77G Radar Test Cell – RF test parameters for ST 77GHz MMIC

TX Output Power Levels

TX Pout vs Frequency

TX off-state power

TX Power Control

TX1 to TX2 Isolation

TX Phase Noise

Power Detectors

TX Peak Detector Sensitivity

Spurious #3 (73.5 GHz to 79.5 GHz)

Temperature Sensor (Sensitivity

and Output Voltage Range)

TX switching speed (TBC)

Amplitude Noise (TBC)

Total conversion gain

Power supply rejection

Input P1dB

Noise Figure

Channel isolation

LO input drive level

IF 3dB bandwidth

Conversion gain imbalance

from channel to channel

Phase imbalance from

channel to channel

Temperature sensor output

Tx Rx

Q-Band Measure Module(s)

Required for MOD

Q-Band Source Module(s)

Required for TX & RX

77GHz Instrument E-Band Measure

Module(s)

Required for TX

E-Band Source

Module(s)

Required for RX

Xce

rra D

UT

inte

rface

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• Plus standard Automotive tests and high-speed digital test of ADC

• Provides highest level of test coverage for guaranteed DUT quality

Conclusions

• Test cell approach, with modular instrumentation and optimized signal interfacing, has been used in production since 2011 to provide a cost-effective solution for full-speed 24GHz testing.

• Same approach is now used for ST 77GHz automotive radar MMICs.

• Signal interface optimization and handler integration allows multi-temperature testing in production

• Result: The Automotive Radar MMICs are tested to the highest levels of coverage, to guarantee premium level quality to the Automotive OEMs.

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Questions?