Impact of Radiation-Induced Single-Event Transients on High Resolution Time to Digital Converter
The paper presents the analysis of radiation-induced Single-Event Transients (SET) in Delay-Locked Loop (DLL) and its impact in the digital output of Time-to-Digital Converter (TDC). The performance of the TDC such as Differential Non-Linearity (DNL),Integral Non- Linearity (INL), resolution etc. are degraded due propagation of the SET from the DLL. The use of improved pseudo differential current-starved delay cell structure in the Voltage Controlled Delay Line (VCDL) in DLL reduces the impact of radiation- induced SET in DLL, and enhances the robustness of DLL based TDC. This effort represents the first of its kind SET analysis on a DLL based TDC. The proposed DLL based TDC is designed in the AMS 180 nm CMOS technology and simulations show that the number of missing pulses on a SET strike in the modified pseudo differential delay cell is reduced to 50% than compared the conventional architectures.
Single Event Transients in Logic Circuits—Load and Propagation Induced Pulse Broadening
The generation and propagation of single event transients (SET) in logic gate chains is studied and modeled. Regarding SET generation, we investigate the dependence of the generated SET pulse width on the struck node capacitance. Rising node capacitance may lead to amplified pulse width, indicating that increasing load capacitance alone is not an option for radiation hardening. SET propagation in logic chains is also studied, and it is shown that significant broadening or attenuation of the propagated transient pulse width may be observed. It is shown that the chain design (propagation delay of high to low and low to high transitions) has a major impact on broadening or attenuation of the propagated transient pulse. For the first time a suitable model for SET broadening is provided.
Contractor Failure: Analysis
The possibility exists for any construction contractor to fail to filfill the contract requirements associated with a facility. Contractor failure occurs when a contractor is unable to perform his/her contractual duties, thus requiring the facility owner to invoke the contract's nonperformance clause. This paper provides aggregate contractor business failure statistics and outlines potential causes for failure. A framework to identify and quantify the associated costs is also introduced. Several case studies are presented to examine the cause and cost of failure and the means by which the facilities were completed. Alternatives available for project completion when contractor failure occurs are discussed. Recommendations to identify and monitor contractors at high risk for failure are outlined as well. This paper provides facility owners with a greater awareness of the possibility of contractor failure, how to quantify costs of contractor failure, and avoidance techniques.