K.B. Crawford

Observation of single event upsets in analog microcircuits

Selected analog devices were tested for heavy-ion-induced single event upset (SEU). The results of these tests are presented, likely upset mechanisms are discussed, and standards for the characterization of analog upsets are suggested. The OP-15 operational amplifier, which was found to be susceptible to SEU in the laboratory, has also experienced upset in space. Possible strategies for mitigating the occurrence of analog SEUs in space are also discussed. >

Single event upset (SEU) sensitivity dependence of linear integrated circuits (ICs) on bias conditions

The single event upset (SEU) sensitivity of certain types of linear microcircuits is strongly affected by bias conditions. For these devices, a model of upset mechanism and a method for SEU control have been suggested.

On the suitability of non-hardened high density SRAMs for space applications

Several non-radiation-hardened high-density static RAMs (SRAMs) were tested for susceptibility to single event upset (SEU) and latchup. Test results indicate that at present only a few such device types are suitable for use in space applications. Several additional factors such as susceptibility to multiple-bit upsets and to radiation induced permanent damage need to be taken into consideration before these device types can be recommended. One nonhardened SRAM device type has recently been used on a low-Earth-orbit satellite, enabling the upset rate measured in space to be compared to that predicted from ground-based testing. >

Single event functional interrupt (SEFI) sensitivity in microcircuits

The single event functional interrupt (SEFI) sensitivity of several types of microcircuits is measured with heavy ions. While simple microcircuits have not been affected by SEFI, many complex microcircuits are vulnerable to it in varying degrees. Although there are many causes for SEFIs, ion irradiation testing in conjunction with an understanding of device architecture helps refine techniques which can be used to lessen the ill effects caused by SEFI.

Single-word multiple-bit upsets in static random access devices

Presents the results of an investigation of the SMU (single-word multiple-bit upset) vulnerability of a number of high density SRAM (static random-access memory) device types. The primary objectives of this study were to examine the extent of SMUs in SRAMs, determine design characteristics that predispose devices to this type of upset, and investigate SMU mitigation techniques applicable to space-based electronic systems. The results reported suggest that a nonnegligible SMU rate can be expected for most high-density SRAM types when exposed to the space radiation environment. However, the range of SMU rates is also very large, suggesting that careful selection of device types should be emphasized during the design phase. Furthermore, susceptibility to SEU is not necessarily a reliable indicator of SMU vulnerability. A more important determinant, in many cases, is the architecture of the device, especially the physical separation between logically adjacent cells. It is therefore inappropriate to consider SEU (single event upset) studies to be a proxy for SMU investigations. >

SEE sensitivities of selected advanced flash and first-in-first-out memories

Single event effects sensitivity measurements of advanced flash and first-in-first-out memories have been made. While many upsets are transients, other upsets initiated by high LET ions are semi-permanent.

Single event effects in pulse width modulation controllers

SEE testing was performed on pulse width modulation (PWM) controllers which are commonly used in switching mode power supply systems. The devices are designed using both Set-Reset (SR) flip-flops and Toggle (T) flip-flops which are vulnerable to single event upset (SEU) in a radiation environment. Depending on the implementation of the different devices the effect can be significant in spaceflight hardware.

Single event transient (SET) sensitivity of radiation hardened and COTS voltage comparators

The single event transient (SET) sensitivity of a radiation hardened voltage comparator type with vertical input transistors is compared with that observed for a COTS device type made up of lateral transistors. The cause of the difference in sensitivity is investigated.

Permanent single event functional interrupts (SEFIs) in 128- and 256-megabit synchronous dynamic random access memories (SDRAMs)

Permanent Single Event Functional Interrupts (SEFIs) have been observed in several high density Synchronous Dynamic Random Access Memories (SDRAMs). Affected devices often lose both Read and Write functions.

Comparative SEU sensitivities to relativistic heavy ions

SEU sensitivity of microcircuits to relativistic heavy ions is compared to that measured with low energy ions of comparable LET values. Multiple junction charge collection in a complex circuit seems to mask the effect of varying charge generations due to different ion track structures. Heavy ions at sub-relativistic speeds may generate nuclear fragments, sometimes resulting in SEUs.