This attempt at circuit level single event effects (SEE) hardening of SiGe HBT logic provides the first reported indication of the level of sensitivity in this important technology. Characterization over data rate up to 3 Gbps and over a broad range of heavy ion LET's provides important clues to upset mechanisms and implications for upset rate predictions. We augment ion test data with pulsed laser SEE testing to indicate the sensitive targets within the circuit and to provide insights into the upset mechanism(s).

The Motion Picture Association of America (MPAA) provides ratings for the majority of commercially released films. The MPAA system is based largely on estimates of what types of film content may be offensive to most parents. We identify four assumptions that underlie the current rating system and show how these assumptions are inconsistent with social science research regarding the impact of media portrayals on young viewers. Finally, we offer an alternative scheme based on what is harmful to children rather than what is offensive to parents. The expansion of cable television and the availability of videocassette recorders have increased the diversity of the home media environment for most families (Dorr & Kunkel, 1990). These new media technologies have also increased the possibility that children will view material that is not necessarily considered appropriate for younger age groups. For example, one survey found that up to 77% of the 14-and 15-year-old respondents reported that they had viewed a number of R-rated films supposedly restricted to viewers over age 17, either in the theater or on videocassette (Creenberg et al., 1986). The vast quantity of adult material now available on cable and on videocassettes places many parents in the position of having to make daily decisions about what their children should and should not view. The Motion Picture Association of America (MPAA) attempts to provide information to viewers, specifically parents, about the content of various movies. This information is conveyed inthe form of ratings that accompany most commercial films and are publicized on most videocassette copies of these 443 444 JOBEM 34:4 Falli 990films. At first glance, the rating system appears to be a useful guide to assist parents in monitoring their children's viewing. The MPAA scheme, however, suffers from a number of problems that limit its utility for parents.We identify four assumptions inherent in the MPAA scheme. We then show how those assumptions are inconsistent with research evidence on the impact of certain media portrayals on young viewers. Finally, we offer an alternative classification scheme that would lead to considerably different ratings than those currently given by the MPAA.

Index Terms-Ground testing, modeling, SiGe, silicon germanium, single event effect, single event upset.

No abstract

Abstract-A new circuit-level single-event upset (SEU) hardening approach for high-speed SiGe HBT current-steering digital logic is introduced and analyzed using both device and circuit simulations. The workhorse D-type flip-flop circuit architecture is modified in order to significantly improve its SEU immunity. Partial elimination of the effect of cross-coupling at the transistor level in the storage cell of this new circuit decreases its vulnerability to SEU. The SEU response of this new circuit is quantitatively compared with three other D flip-flop architectures, including the unhardened circuit, a conventional NAND gate based circuit, and a current-sharing hardened (CSH) circuit, at both variable data rate and switching current. The new circuit shows substantial improvement in SEU response over the unhardened version, with little increase in layout complexity and power consumption. While the NAND gate based circuit still shows better SEU response than the other circuits, its high power consumption will preclude its use in space applications. Our results suggest that this new circuit architecture exhibits sufficient SEU tolerance, low layout complexity, and modest power consumption, and thus should prove suitable for many space applications requiring very high-speed digital logic.