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Testing of Digital Systems - Introduction 1
stems
les
(ESLAB)
/test/index.html
Zebo Peng, ESLAB, LiTH
Testing of Digital Sy
Zebo Peng and Petru E
Embedded System Laboratory
Linköping University
http://www.ida.liu.se/~zebpe/teaching
Testing of Digital Systems - Introduction 2
m testing.
synthesis.
Zebo Peng, ESLAB, LiTH
Contents
☞ Basic principles and practice of digital syste
☞ Design for testability techniques.
☞ Integration of test consideration with system
☞ Testing of system-on-chip.
Testing of Digital Systems - Introduction 3
ipants.
edman, “Digital Systemcience Press, 1990.
Zebo Peng, ESLAB, LiTH
Cour se Organization
☞ General lectures.
- Lecture notes and selected papers.
☞ Seminars and discussions, led by the partic
- M. Abramovici, M. A. Breuer and A. D. FriTesting and Testable Design,” Computer S
- Seminar notes by the participants.
Testing of Digital Systems - Introduction 4
tion
Zebo Peng, ESLAB, LiTH
Lecture I: Introduc
1. Basic definition and terminology
2. Classification of test
3. Test process
4. Test cost and its reduction
Testing of Digital Systems - Introduction 6
g its resulting response tohe manufacturing or opera-
g its resulting response to
nctions correctly.
Zebo Peng, ESLAB, LiTH
What is T esting?
☞ Process of exercising a product and analyzincheck whether faults are introduced during ttion phase.
☞ Process of exercising a product and analyzincheck whether it functions correctly.
☞ Process of determining whether a product fu
Testing of Digital Systems - Introduction 7
e
esting
TestPreparation
ionn
onon
Zebo Peng, ESLAB, LiTH
Hardware Lif e Cycl
Specification
Design
Implementation
Manufacturing
Production Test
Operation andMaintenance
TSystem Integration
System Test
VerificatValidatio
Simulati
ReviewInspecti
Testing of Digital Systems - Introduction 8
ital Systems
Physical faults
Zebo Peng, ESLAB, LiTH
Causes of Incorrect Function of Dig
• Design errors usually consistent
• Fabrication (manufacturing) errors
- often consistent, e.g., wrong components
- usually operator errors
• Fabrication (manufacturing) defects
- inconsistent, e.g., impurity of materials
• Physical failures
- wear-out
- environmental factors
Testing of Digital Systems - Introduction 9
F aults
urrence.
rvals.
y a temporary change in
Zebo Peng, ESLAB, LiTH
Classification of Ph ysical
☞ Permanent always present after their occ
☞ Intermittent existing only during some inte
☞ Transient a one-time occurrence cased bsome environmental factor.
Testing of Digital Systems - Introduction 10
of CUT (circuit under test)
meter is changed (e.g.,
Zebo Peng, ESLAB, LiTH
Another Classification
☞ Logic (functional) faults the logic functionis wrong.
☞ Parametric the magnitude of a CUT parapower and current).
Testing of Digital Systems - Introduction 13
ut pins.
e so as to make contact
M application).
Zebo Peng, ESLAB, LiTH
Test Head Fixtures
• Edge-connector via the normal input/outp
• Bed of nails.
• Wafer prober a set of micro-probes arrangwith the bonding pads of a chip.
- Bare chip test for known-good die (for MC
- Wafer-level screening.
• Probes:
- Mechanical probe.
- Electron-beam probe.
Testing of Digital Systems - Introduction 14
ting
impossible.
st data.
Long test application time.
r/sensor mechanism and
opment efforts.
gn process.
Zebo Peng, ESLAB, LiTH
Main Difficulties in T es
• Miniaturization -> Physical access difficult or
• Increasing complexity -> Large amount of te
• Number of access ports remains constant ->
• High speed -> High demand on tester’s drivemore complicated failure mechanism.
-> Testing accounts up to 50% of product devel
☞ The key to successful testing lies in the desi
Testing of Digital Systems - Introduction 15
FT)
ing the design process so.
ble.
Zebo Peng, ESLAB, LiTH
Design f or Testability (D
☞ To take into account the testing aspects durthat more testable designs will be generated
☞ The design is changed to make it more testa
☞ Advantages of DFT:
- Reduce test efforts.
- Reduce cost for test equipments (ATE).
- Shorten turnaround time.
- Increase product quality.
Testing of Digital Systems - Introduction 16
(fault site and fault type).
ce manufacturing errors).
):
ossible faults.
: based on the erroneousould produce it.
Zebo Peng, ESLAB, LiTH
Test vs. Dia gnosis
• Test Detection of faults.
• Diagnosis Detection and location of faults
- Repair.
- Manufacturing process optimization (redu
- Re-design.
• Cause-effect analysis (external fault location
- Build a fault dictionary.
- Use dictionary look-up to determine the p
• Effect-cause analysis (internal fault location)response, determine directly the faults that c
- Ex. guided-probe testing.
Testing of Digital Systems - Introduction 17
idual products to checkufacturing phase.
environment to ensure thatther components.
duct in the filed for diagno-
faults during the system
Zebo Peng, ESLAB, LiTH
Types of T esting
• Production (manufacturing) test test indivwhether faults are introduced during the man
• System test test a product in its operatingit works correctly when interconnected with o
• Operation and maintenance test test a prosis or "preventive" purpose.
• Prototype test testing to check for design development phase. Diagnosis is required.
• Different levels: chip, board, or system.
• On-line, off-line, or concurrent testing.
Testing of Digital Systems - Introduction 18
t’ d)
ation with respect to its
, such as open, stack-at,
e internal nodes.
endent parameters, such
ing analog measurements circuit when all nodes are
Zebo Peng, ESLAB, LiTH
Types of T esting (Con
• Functional test validating the correct operfunctional specification.
• Structural test testing of structural defectsand short-circuit.
• Static v. at-speed testing.
• In-circuit test the tester gains access to th
• Parametric test testing of technology-depas power consumption.
• IDDq test testing the entire circuit by makof IDD which is the current flows in a CMOSin the quiescent state.
Testing of Digital Systems - Introduction 21
ess
anufacturing
esign
st Mechanism
Zebo Peng, ESLAB, LiTH
A Typical T esting Pr oc
Test Strategy
Test Generation
Test Evaluation
Test Application
Analysis and
Selection
Diagnosis
M
D
Te
Testing of Digital Systems - Introduction 22
Costs
ections.
n and analysis).
"burn-in" purpose).
Zebo Peng, ESLAB, LiTH
Composition of T esting
• Cost of test equipment (hardware):
- A test controller (usually a computer).
- Interface drivers/receivers and cable-conn
- System of probe-contacts.
- A controlled environment.
• Cost of software supports:
- Test pattern generation programs.
- Test evaluation procedures (fault simulatio
• Testing time
- Test development time.
- Test application time (maybe very long for
Testing of Digital Systems - Introduction 23
of T ens”)
Field
>$500.00
Zebo Peng, ESLAB, LiTH
Cost of Finding Def ects (“Rule
Chip Board System
$0.50$5.00
$50.00
Testing of Digital Systems - Introduction 24
uction
ation, which decreases de-
, i.e., lower fault levels and
t equipment and supports
r functional test which has
st cost.
Zebo Peng, ESLAB, LiTH
Methods f or Test Cost Red
☞ DFT simplifies/automates test pattern genervelopment cost and lead times.
☞ DFT facilitates more efficient production testshorter test application times.
☞ BIST can reduce the need for expensive tesfield test.
☞ Better design verification reduces the need folong test application time.
☞ Statistics-based methods reduces overall te
Testing of Digital Systems - Introduction 25
nd is becoming more diffi-hips, especially systems-
cost.
ical faults introduced dur-.
lts!
Zebo Peng, ESLAB, LiTH
Summar y
☞ Testing is an expensive and complex task, acult with the development of more complex con-chip.
☞ It takes typically 30% of the total production
☞ Hardware testing is mainly used to find physing the manufacturing and operation phases
☞ Testing does not guarantee the absent of fau