alec stanculescu, fintronic usa alex zamfirescu, asc mapld 2004 september 8-10, 2004

Alec Stanculescu, Fintronic USAAlex Zamfirescu, ASC

MAPLD 2004September 8-10, 2004

[email protected] [email protected]

Design Verification Method forRadiation Hardness using

Simulation Farms

Fintronic USA

Stanculescu 2 2004 MAPLD/104

Summary

• Problem Addressed• Solution Proposed• Conclusion• Proposed Plan

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Introduction

• Circuits malfunction due to radiations– Transient errors may lead to Soft

errors if an erroneous data is latched– Cumulative effects may lead to

permanent ( hard) errors (total dose)

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Problem Addressed

• Reduce the cost of assessing the behavior of very large circuits under different radiation conditions by providing fast feedback to circuit designers regarding:– statistics of faults – reliability – nature of degradation

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Solution Proposed

• Simulate radiation effect by injecting faults in the simulation based on the radiation failure susceptibility of the library cells used

• Use efficiently a simulation farm• Automate the analysis of results

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Radiation Hardness Analyzer

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Radiation Failure Susceptibility

• For each cell, for each wire, record– <time window> <fault_info_triplet>+

• <fault_info_triplet> ::= <p of a given fault-type occurring in the

given window>, <type of fault>, <p of at most one fault of the given

type occurring in the given window>;where p stands for probability

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Creation of Radiation Failure Susceptibility Data

• Calibration of Simulation– High correlation between simulation

results and manufactured circuit

• Calibration Methods– Test all cells at various radiation

environments

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Calibration Methods

• Fabricate all supported cells on tested chip – selection of tests may affect calibration

• Use existing circuits for testing• Use an un-hardened version of the

actual circuit• Use transistor susceptibility based

on specific measurements

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FinFarm:Verilog Simulation Farm

• Enables one engineer to manage many simultaneous simulations – Network of computers– Farming methodology – Farming tools

• Current farms use between 10 and more than 1000 licenses

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Farming Methodology

• Un-partitioned circuits • small footprint & 64-bit simulation helps

• Split stimulus• Simultaneous verification of

alternative components• Program feedback-based

verification

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Farming Tools• Perform automated

– simulation launching – simulation queuing– collection & reporting of simulation

results– collection & merging of code

coverage results• Perform real-time monitoring• Perform programmed re-launching

of simulations

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FinFarm™ Usage

• Regression Testing• Extensive Exploration of Design

Space• Evaluation of Reusable IPs• Analysis of Design Trade-Offs: Power,

Size, Speed and search for optimal solution using feedback loop

• Radiation Hardening

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Rad. Hard. Simulation

• Describing effects on circuit by a given radiation environment, using VCD-F format (VCD fault format)

• VCD-F Reader injects corresponding faults in simulation

• Launching simultaneous simulations using simulation farm

• Collecting and processing results

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VCD-F Format

• VCD IEEE std 1364 results• VCD-F specifies random faults, i.e.

values are replaced by:– Fault types– Randomization info

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VCD-F Reader

• VCD-F Reader injects faults in simulation.

• Nature of faults: permanent, transient

• Kind of faults: stuck at, bridging, cross talk, gate rupture, value toggle, timing, etc.

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Simulation Launching

• Save simulations at various check points, just before inserting faults

• Re-start simulation at latest checkpoint before the injected fault which caused errors

• Launch simultaneous simulations on FinFarm™

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Collecting and Processing Results

• Record results databases• Compare Results Databases• Isolate circuits containing at least

one error, for detailed analysis• List of possible fault type• Produce reports

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Summary of Solution

• Cells are measured once and results are stored in IEEE standard

• Use Monte Carlo technique to establish radiation susceptibility of complex ICs using simulation

• Fast feedback to designers• Major cost reduction

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Proposed Plan

• Establish a radiation assessment lab

• Create oversight task force – Government– Industry – Academia

• Create standards for describing– Radiation failure susceptibility of cells– Distribution of faults in circuits in time

alec stanculescu, fintronic usa alex zamfirescu, asc mapld 2004 september 8-10, 2004

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