The heavens have fascinated people since the beginning of mankind. Space travel and exploration remain a popular topic to all ages and are the subjects of international debate, pride, strength and domestic security. The US certainly prides itself in the amazing feat of manned lunar landings in the late 60s and early 70s. A feat not repeated again in 40 years since those first steps were taken by Neil Armstrong.
Science fiction involving space travel continues to fill our entertainment media, and most of us have heard those famous words of Star Trek’s Captain James T. Kirk, “Space – the final frontier!” For those of us who work in the industry, however, we quickly must separate fiction from fact. And we quickly find out that “space is actually a very deadly frontier.” Space is an extremely harsh environment, not only for humans but for electronics as well. Our atmosphere assists in additional shielding of incoming radiation, but produces terrestrial neutrons in this shielding process. These neutrons can produce logic upsets in electronic circuits by impacting other atoms releasing small amounts of energy, changing the material properties and producing energy pulses, causing “glitches” in integrated circuits. As semiconductor feature sizes shrink, the task of making circuits more immune to these effects, or hardening them against these effects, becomes more difficult.
Space, unlike the shielded environment in which we live, can be very dangerous. Low earth orbiting (LEO) spacecraft and satellites are exposed to these protons, electrons and heavy ions from space radiation. Geostationary orbiting (GEO) satellites during a 10–15 year mission will encounter large doses of radiation. Even with shielding they receive enough radiation to kill humans in just a few months. Shielding can help, but only to a limited degree. There is a point of diminishing return where shielding is no longer beneficial. Systems must be designed to operate in this difficult environment, and at the heart of these systems are the electronic components. Special semiconductor processes can be used along with special design techniques to ensure that circuits can operate reliably over long periods of time in space.
Our daily lives are more dependent on data sent or received over satellite systems than ever before. Whether it is international communication, music, DTV, GPS, weather gathering, surveillance, national security, etc., we rely on these systems to function properly every day.
Building circuits that can tolerate radiation effects are necessary for space and aircraft as well as today’s medical applications. Dental and medical X-ray diagnostic equipment now use electronic imaging and data conversion chips to capture images, when photographic film was previously used. These circuits must be able to withstand daily low doses of radiation in these medical and diagnostic applications.
Texas Instruments’ High Reliability group (HiRel) is a major supplier of radiation tolerant semiconductors. Circuits are developed and tested against the various radiation effects that can be encountered in medical, avionics and space applications. It just makes sense to use HiRel products in High Reliability systems. It is very important to not only understand the environment that products are going to be used in, but also that the circuits are reliable and tolerant in the specific application.
Author InformationJames F. Salzman is the Director of Technology for TI’s HiRel organization. With more than thirty years of engineering experience, James has spent a full decade focused on developing radiation-hardened technology and products. A Distinguished Member of Technical Staff at TI, James has three patents registered and four pending. He received his Electrical Engineering degree from Southern Methodist University, Dallas, Texas
James is also a Senior Member IEEE, Registered Professional Engineer in Texas, authored or coauthored of over 20 papers on radiation effects. Received Best Paper Award in 2008 at the Hardened Electronics and Radiation Technology Conference, and is Member of the IEEE Nuclear Science. James can be reached at
ti_jamessalzman@list.ti.com.
