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L i a b l eh kC o m p u t i n gL a b o r a t o r y Trace-Based Post-Silicon Validation for VLSI Circuits Xiao Liu Department of Computer Science and Engineering.

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Presentation on theme: "L i a b l eh kC o m p u t i n gL a b o r a t o r y Trace-Based Post-Silicon Validation for VLSI Circuits Xiao Liu Department of Computer Science and Engineering."— Presentation transcript:

1 l i a b l eh kC o m p u t i n gL a b o r a t o r y Trace-Based Post-Silicon Validation for VLSI Circuits Xiao Liu Department of Computer Science and Engineering The Chinese University of Hong Kong

2 Silicon Debug: Bottleneck in Prototype-to- Volume Time Pre-silicon verification cannot ensure the design correctness Smaller design margins – increasing chance of performance failures Un-modeled defects – higher tester escapes Higher design complexity – more time and vectors to validate Acknowledgment: Yu-Chin Hsu, Furshing (Kevin) Tsai, Wells Jong, Ying- Tsai Chang, Novas Test/DebugDesign Silicon Prototype ConceptVolume 7 to 8 months Decreasing 6 to 7 months Increasing! Data Quest (2002, 2004) report

3 Post-Silicon Validation Problem Post-silicon validation is expensive One respin: millions of $ Economic impact of delayed ramp to production: tens of millions $ Post-silicon validation is challenging Very limited observability Scan is not enough Industry silicon spins 12345 or above 0% 10% 20% 30% 40% 50% ASSPASIC source: Numetrics Management Systems, Inc.

4 Trace-Based Post-Silicon Validation Pro Observe the system’s behavior in real-time Exercise functionality and timing not verified pre-silicon Detect problem difficult to reproduce on tester Con Low coverage Hardware overhead Debug Configuration Data Analysis, Diagnosis Design-for-Debug Insertion Data dump Acknowledgment: Yu-Chin Hsu, Furshing (Kevin) Tsai, Wells Jong, Ying- Tsai Chang, Novas How to conduct signal tracing effectively with low-cost hardware?

5 Trace-Based Post-Silicon Validation Infrastructure [DATE-09, ATS-10, DATE-11] [ATS-08, DAC-09]

6 Tracing Solutions for Debugging Design Error Design errors violate the pre-defined specification Signal selection for visibility enhancement [DATE-09] Challenge: Logic values are not known during signal selection Solution: Traced signal 01234 AXXXXX BXXXXX C0110X DXXXXX EXXXXX 01234 A11XXX B00XXX C0110X DX1001 EX10XX Visibility estimation metricTrace signal selection Guide Our solution achieves higher visibility

7 Tracing Solutions for Debugging Design Error Design errors violate the pre-defined specification Multiplexed tracing [DATE-11] Trigger point Trace buffer size Current solution: “static” tracing Time Trigger point Trace buffer size Time Proposed solution: “multiplexed” tracing Trace those FFs with propagated evidences facilitates to detect this error Our solution provides higher design error detection capability

8 Tracing Solution for Debugging Electrical Error Electrical errors lead to reduced frequency of the circuits Sensitive to electrical environment Coupling noise, Power supply noise, Driving strength, … Extremely difficult to eliminate during pre-silicon verification and manufacturing test Challenge: Difficult to localize in post-silicon validation Solution: in-situ tracing Selectively trace signals that monitors potential errors on speedpaths Our solution can detect error At its root-cause site On error occurrence cycle Without “golden vectors”

9 Low-Cost Trace Data Transfer Fabric Design Challenge: High flexibility v.s. Low cost Solution: Interconnection fabric design [DAC-09] Signal classification Design optimization Challenge: High Bandwidth v.s. Low cost Solution: Reusing test access mechanism [ATS-08] Challenge: Systematical tracing v.s. Low cost Solution: Flexible interconnection fabric design Non-correlated signals Correlated signals Our solution minimizes hardware cost Our solution reduces routing cost Our solution enables systematical tracing

10 Thank you for your attention !

11 Backup Slides Trace signal selection for visibility enhancement   Multiplexed tracing for detecting design error   Interconnection fabric design   Signal tracing for debugging electrical error  

12 Experimental Results of Signal Selection for Visibility Enhancement 

13 Experimental Results of Multiplexed Tracing 

14 DfD Cost Comparison of s38417 

15 Speedpath-Related Electrical Errors Model Trace those FFs that make the above node values visible facilitates to detect this error Required visible node values: a_in2(0), b_in1(0), c_out(0) 

16 Detection Quality Evaluation: Signal Selection for Non-Zero Visibility CircuitTotal Signal # Relevant Signal # Selected Signal # Detected Pro. Event # Occurred Pro. Event # Detection Quality Time (s) s385841464198697718951981.1%45.5 s384171664394157630121651.8%125.3 DMA38181482996827761589.6%150.3 usb208511759696 100%77.4 des934113295670977014595.6%668.3 


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