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Reliability of some modularly redundant systems
WORLD
ABSTRACTS
ON MICROELECTRONICS
the ~ 8ympo6um ms P_@_'_,~__7_;ey,J U S E , Tokyo, Japan. 17-18 April (1972), p. 475. (In Japanese.) In 8eneral, parallel redundancy is divided into component redundancy and system redundancy. It is well known that the reliability of component-redundant system is always higher than that of ~tem-redundant system under the eonditkm of independent failures. However, in the componant-redundant eyetem where components are mutually dose, there are intera~om between cornponent failures, that is, dependent faihtres. Therefore, in order to develop the eorrect system reliability, we must consider the reliability of redundant systems with dependent failures. In this paper we introduce a measure for failure dependency and discuss the comparison of reliabilities of both redundant systems. R e l i a ~ l i t y o( s o m e m o d u l a r l y r e d m u l a n t s y s t e m s . D. K. CHOW. I E E E Tram. Rdiab. R-21, No. 2, May (1972), p. 67. A mathematical model is established for the reliability of modularly redundant systems with unequal failure rates for the operating and standby units, The failure modes include failures of the active and standby units, three types of switch failures and failures on system recovery. System reliability is considered for cases of both similar and dissimilar units, and for various restrictions on the failure parameters. It is shown that the most important failure parameters are those related to catastrophic failures, and that putting more reliable units as basic units, which operate initially, is important when switches and recovery are imperfect, Circuit m o d e l distribution w i t h statistical d e p e n d e n c e . C. A. Kaolin. I E E E Tram. Reliab. ]11-21, No. 2, May (1972), p. 70. Guidelines are presented for structuring a reliability model where detailed failure modes are considered explicitly and where no assumption of statistical independence is made between the failure modes. An electronic circuit is considered. Part and interface characteristics, performance attribute and stress equations and conditional reliability relationships are fitted together. Pertinent features are illustrated with
AND RELIABILITY
479
examples. A compoaite reliability prediction equation in hmctional notation is in~sented. T h e required information is the same type which is used for separately trmtin8 detailed failure modes. However, this information needs to be accurate to warrant a model with statistical dependance, and this would be di~eult. Numerical cslmdatiom are tediotm and expemive, even where computerized. E~erimental applications are necessary to determine if this detailed reliability prediction model has anything practical to offer. C o m p u t e r - a i d e d rellab/iity anal]ntis c~ c o m p l i c a r e d networlm. E. V. K a m m q ~ and G. KommSAa. I E E E Tra~. Rdiab. R-21, No. 2, May (1972), p. 86. A computer-aided procedure is described for analyzing the reliabilityof complicated networks. This procedure breaks down a network into small subnetworks whose reliability can be more readily calculated. T h e subnetworim which are searched for are those with only two nodes; this allows the original network to be considerably simplified. F a u l t ident/flcatton in e l e c t r o n i c c i r c u l / s w i t h t h e a i d o( b l l l n ~ t r t r a n m ~ a t i o m m . G. O. MARTENSand J . D . DYCK. I E E E Tram. Rdiab. ][-21, No. 2, May (1972), p. 99. A method has been developed for applying bilinear transformations to the identification of faulty components in linear electronic circuits. Simple magnirude and phase measurements, at a number of test frequencies, are made and plotted On a set of predetermined loci in the complex transfer-function plane. The data for plotting the loci are determined either experimentally or by circuit analysis with a digital computer. T h e faulty component and the parameter value are then determined from the loci. The method has the advantage that it pmvidesagraphicai representation of thecircuitbehavior with a faulty component and also readily allows experimental error to be taken into account when plotting the measured data. The method is demonstrated with a practical transistor amplifier circuit.
4. M ] C R O E I ~ C T R O M C ~ - G ~ F u n d a m e n t a l l i m i t a t i o n s in m l c r o e l e c t r o n l c s . I. M O S t e c h n o l o g y . B. HomN~sl~ and C. A, M ~ . So/id St. E / ~ r o n . 15 (1972), p. 819. T h e physical phenomena which will ultimately limit M O S circuit miniaturization are considered. It is found that the minimum M O S transistor size is determined by gate oxide breakdown and drain-source punch-through, Other factors which limit device size are drain-substrate breakdown, drain "comer" breakdown and substrate doping fluctuations. However, these limitations are less severe than the oxide breakdown limitation mentioned above. Power diuipation end metal migration limit the frequency and/or packing density of fully dynamic and of complementary M O S circuits. In static non-complementary circuits, power dissipation is the principal limitation of the number of circuit functions per chip.
The charmel length of a minimum size M O S transistor is a factor of I'0 smaller than that of the smallest presentday devices. T h e tolerances required to manufacture such a transistor are compatible with electron beam masking techniques. It is thus possible to envisase fully dynamic silicon chips with up to 10~-10 s M O S tranaistors per cm I. R a d i a t i o n effects o n m l c r o e l e c t r o u l c c o m l m m e a t s a n d circuits, P a r t 1. L. W. l~cK~rt~. Solid St. Technol., April (1972), p, 50. This article presents an overview of radiation effects on microelectronic components and circuits and will be presented in two parts. Part 1 covers the environmant, comparative xadiation effects, equivalent circuits of devices exposed to radiation and the general effects on typical microelectronic devices.
ABSTRACTS
ON MICROELECTRONICS
the ~ 8ympo6um ms P_@_'_,~__7_;ey,J U S E , Tokyo, Japan. 17-18 April (1972), p. 475. (In Japanese.) In 8eneral, parallel redundancy is divided into component redundancy and system redundancy. It is well known that the reliability of component-redundant system is always higher than that of ~tem-redundant system under the eonditkm of independent failures. However, in the componant-redundant eyetem where components are mutually dose, there are intera~om between cornponent failures, that is, dependent faihtres. Therefore, in order to develop the eorrect system reliability, we must consider the reliability of redundant systems with dependent failures. In this paper we introduce a measure for failure dependency and discuss the comparison of reliabilities of both redundant systems. R e l i a ~ l i t y o( s o m e m o d u l a r l y r e d m u l a n t s y s t e m s . D. K. CHOW. I E E E Tram. Rdiab. R-21, No. 2, May (1972), p. 67. A mathematical model is established for the reliability of modularly redundant systems with unequal failure rates for the operating and standby units, The failure modes include failures of the active and standby units, three types of switch failures and failures on system recovery. System reliability is considered for cases of both similar and dissimilar units, and for various restrictions on the failure parameters. It is shown that the most important failure parameters are those related to catastrophic failures, and that putting more reliable units as basic units, which operate initially, is important when switches and recovery are imperfect, Circuit m o d e l distribution w i t h statistical d e p e n d e n c e . C. A. Kaolin. I E E E Tram. Reliab. ]11-21, No. 2, May (1972), p. 70. Guidelines are presented for structuring a reliability model where detailed failure modes are considered explicitly and where no assumption of statistical independence is made between the failure modes. An electronic circuit is considered. Part and interface characteristics, performance attribute and stress equations and conditional reliability relationships are fitted together. Pertinent features are illustrated with
AND RELIABILITY
479
examples. A compoaite reliability prediction equation in hmctional notation is in~sented. T h e required information is the same type which is used for separately trmtin8 detailed failure modes. However, this information needs to be accurate to warrant a model with statistical dependance, and this would be di~eult. Numerical cslmdatiom are tediotm and expemive, even where computerized. E~erimental applications are necessary to determine if this detailed reliability prediction model has anything practical to offer. C o m p u t e r - a i d e d rellab/iity anal]ntis c~ c o m p l i c a r e d networlm. E. V. K a m m q ~ and G. KommSAa. I E E E Tra~. Rdiab. R-21, No. 2, May (1972), p. 86. A computer-aided procedure is described for analyzing the reliabilityof complicated networks. This procedure breaks down a network into small subnetworks whose reliability can be more readily calculated. T h e subnetworim which are searched for are those with only two nodes; this allows the original network to be considerably simplified. F a u l t ident/flcatton in e l e c t r o n i c c i r c u l / s w i t h t h e a i d o( b l l l n ~ t r t r a n m ~ a t i o m m . G. O. MARTENSand J . D . DYCK. I E E E Tram. Rdiab. ][-21, No. 2, May (1972), p. 99. A method has been developed for applying bilinear transformations to the identification of faulty components in linear electronic circuits. Simple magnirude and phase measurements, at a number of test frequencies, are made and plotted On a set of predetermined loci in the complex transfer-function plane. The data for plotting the loci are determined either experimentally or by circuit analysis with a digital computer. T h e faulty component and the parameter value are then determined from the loci. The method has the advantage that it pmvidesagraphicai representation of thecircuitbehavior with a faulty component and also readily allows experimental error to be taken into account when plotting the measured data. The method is demonstrated with a practical transistor amplifier circuit.
4. M ] C R O E I ~ C T R O M C ~ - G ~ F u n d a m e n t a l l i m i t a t i o n s in m l c r o e l e c t r o n l c s . I. M O S t e c h n o l o g y . B. HomN~sl~ and C. A, M ~ . So/id St. E / ~ r o n . 15 (1972), p. 819. T h e physical phenomena which will ultimately limit M O S circuit miniaturization are considered. It is found that the minimum M O S transistor size is determined by gate oxide breakdown and drain-source punch-through, Other factors which limit device size are drain-substrate breakdown, drain "comer" breakdown and substrate doping fluctuations. However, these limitations are less severe than the oxide breakdown limitation mentioned above. Power diuipation end metal migration limit the frequency and/or packing density of fully dynamic and of complementary M O S circuits. In static non-complementary circuits, power dissipation is the principal limitation of the number of circuit functions per chip.
The charmel length of a minimum size M O S transistor is a factor of I'0 smaller than that of the smallest presentday devices. T h e tolerances required to manufacture such a transistor are compatible with electron beam masking techniques. It is thus possible to envisase fully dynamic silicon chips with up to 10~-10 s M O S tranaistors per cm I. R a d i a t i o n effects o n m l c r o e l e c t r o u l c c o m l m m e a t s a n d circuits, P a r t 1. L. W. l~cK~rt~. Solid St. Technol., April (1972), p, 50. This article presents an overview of radiation effects on microelectronic components and circuits and will be presented in two parts. Part 1 covers the environmant, comparative xadiation effects, equivalent circuits of devices exposed to radiation and the general effects on typical microelectronic devices.