Post on 12-Jan-2016
vargas@computer.org 1
Test Based on Current Monitoring:
IDDq Testing
vargas@computer.org 2
Up to now, fault-tolerance has been based on the observation of system logic states.
The next slides describe a new paradigm: decide if the system is correct or faulty by observing the current (IDDq) consumption.
This approach is also based on HW redundancy, since extra logic is placed
on-board or on-chip in the form of dedicated chips or IP-cores, respectively.
vargas@computer.org 3
Em 1963 Frank Wanlass (Fairchild Semiconductor) publicou o conceito de circuito CMOS. Ocorreu-lhe que um circuito CMOS usa muito pouca potência quando em standby, na verdade a única corrente que fluiria seria a corrente de leakage.
What is IDDq?
vargas@computer.org 4
Reference Paper:
Mark W. Levi in his ITC’1981 paper (“CMOS is most Testable”, Proceedings of ITC’81, pp. 217-220).
What is IDDq?
vargas@computer.org 5
What is IDDq?
Faulty Behavior
vargas@computer.org 6
What is IDDq?
Faulty Behavior
vargas@computer.org 7
What is IDDq?
Mede a corrente de entrada em condição de steady state.
Nenhum caminho direto entre VDD e Gnd.
Sem defeito -> alta impedância entre VDD e Gnd no estado quiescente!
Se o IC puxa corrente -> defeito!
vargas@computer.org 8
Determinar o threshold
Muito alto (qual o problema?)
Muito baixo (qual o problema?)
Dificulties involved with IDDq Monitoring
vargas@computer.org 9
Dificulties involved with IDDq Monitoring
vargas@computer.org 10
Devemos jogar todos os CIs com IDDq anormal no lixo, mesmo que passem em outros tipos testes?
Dificulties involved with IDDq Monitoring
Sim !
vargas@computer.org 11
Types of Defects Detected by IDDq Monitoring
vargas@computer.org 12
O teste de IDDQ é mais difícil para 130-nm ou processos menores, porque o ruído no circuito dificulta a distinção entre o dispositivo bom e o com falha.
IDDq and Technology Scaling
vargas@computer.org 13
Goal: IDDQ fault coverage of 95% or greater
IDDq Fault Coverage
vargas@computer.org 14
Módulos Monitores On-Board
Chips monitores que são colocados na placa
Techniques for Measurements (1)
vargas@computer.org 15
Módulos Monitores On-Board
Chips monitores que são colocados na placa
Techniques for Measurements (1)
vargas@computer.org 16
On-Board Test Controller (or Automatic Test Equipment )
Synchronization
Módulos Monitores On-Board
Chips monitores que são colocados na placa
Techniques for Measurements (1)
vargas@computer.org 17
Módulos Monitores On-Chip
Núcleos IP monitores que são colocados on-chip
Techniques for Measurements (2)
ICCD 1988
vargas@computer.org 18
Techniques for Measurements (2)
Módulos Monitores On-Chip
Núcleos IP monitores que são colocados on-chip
vargas@computer.org 19
Techniques for Measurements (2)
Módulos Monitores On-Chip
Núcleos IP monitores que são colocados on-chip
vargas@computer.org 20
Techniques for Measurements (2)
Módulos Monitores On-Chip
Núcleos IP monitores que são colocados on-chip
vargas@computer.org 21
Techniques for Measurements (3)
vargas@computer.org 22
1K x 1bit SEU-Tolerant SRAM Chip with Core Size: 3.5 X 4.6mm2
Techniques for Measurements (3)
vargas@computer.org 23
Thank you for your attention