4. Built-In Self Test (BIST): Periodical Off-Line Test on the Field

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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.1 General Structure

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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.2 Pattern Generator

General Structure of an n-1 Stage Linear
Feedback Shift Register (LFSR).
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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.2 Pattern Generator

Example of a 4-Bit LFSR as a Pattern Generator.
Pseudorandom States Generated by the LFSR.
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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.3 Signature Generator

Serial
r-Bit (Internal XOR) Signature Generator. The
content of the LFSR is the remainder of the
division operation.
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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.3 Signature Generator

Serial
r-Bit (External XOR) Signature Generator. The
content of the LFSR is not the remainder of the
division operation.
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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.3 Signature Generator

Serial
Example of a 4-Bit (External) Signature
Generator.
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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.3 Signature Generator

Parallel
r-Bit (Internal XOR) Parallel Signature
Generator. The content of the LFSR is not the
remainder of the division operation.
r-Bit (External XOR) Parallel Signature
Generator. The content of the LFSR is the
remainder of the division operation.
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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.3 Signature Generator

Problem When compacting results, there is a
probability of fault masking ! Probability of
failing to detect an error in the response
sequence
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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.4 Example 8-bit-Length Datapath

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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.4 Example 8-bit-Length Datapath

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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.4 Example 8-bit-Length Datapath

Signature Generator (External XOR). Parallel
Pattern Generator (External XOR) all inputs Zs
equal to 0.
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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.5 Built-In Logic Block Observer (BILBO)

Example of a BILBO structure.
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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.5 Built-In Logic Block Observer (BILBO)

Modular Bus-Oriented Design with BILBO.
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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.6 Transparent BIST for Memory Test

Transparent Built-In Self Test is a test
algorithm that is periodically executed on the
field in order to verify the integrity of large
amounts of critical data stored on mass memory
systems
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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.6 Transparent BIST for Memory Test

• Main characteristics
• a) Minimum area overhead this approach is one of
  the best choices found in the literature in terms
  of area overhead and types of faults detected in
  memory structures. E.g., authors claim an area
  overhead of 1.2 due to the inclusion of
  Transparent BIST in a 128Kbytes X 8bytes SRAM
  (this value decreases as the RAM size increases).

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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.6 Transparent BIST for Memory Test

• Main characteristics
• b) High capability of fault detection by
  indicating the occurrence of stuck-at faults,
  transition faults, coupling faults, decoder
  faults and read/write logic faults.

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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field

• 4.6 Transparent BIST for Memory Test

• Main characteristics
• c) Short down times that are periodically
  required to check the functionality of mass
  memory systems used in real-time applications.
  The Transparent BIST approach presents the
  incomparable advantage of preserving the contents
  of the RAM memory after testing. Thus, this
  approach is very suitable for periodic testing
  since we do not need to save the memory contents
  before the test session and to restore them at
  the end of this session.

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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field
 
 

• 4.6 Transparent BIST for Memory Test

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4. Built-In Self Test (BIST)Periodical
Off-Line Test on the Field
 

• 4.6 Transparent BIST for Memory Test

• Note that the data read during the execution of
  sequences S1 through S4 of the signature
  prediction algorithm (Table 2) are sometimes
  inverted in order to match the data read during
  the execution of sequences S1 through S4 of the
  Transparent BIST (Table 1).