RadCell Fox™ Die-Level Reliability Monitor

Total dose radiation exposure results in charged defect densities in the isolation and gate oxide regions of a MOS transistor. Charged defects degrade device performance by introducing changes in threshold leakage current and voltage. The magnitude of the parametric shift is dependent on operating conditions and environment.

The Ridgetop RadFox prognostic cell accurately senses the radiation-induced leakage current in CMOS transistors and outputs the cumulative degradation result. It is part of the Sentinel Silicon™ library of prognostic (“canary”) cells.

The prognostic distance is the time between the prognostic cell warning point and the time of system failure, as shown below. The prognostic distance of the RadFox prognostic cell can be adjusted to meet customer needs by trigger point calibration.


  • Acts as an early-warning sentinel of an upcoming leakage failure condition caused by radiation exposure
  • Size: 800 μm2 at the 0.25 micron process size
  • Available for 0.35, 0.25, and 0.18 micron CMOS processes
  • Power dissipation is approximately 50 μW
  • Prognostic distance can be adjusted from the nominal 80% point
  • Simple buffered logic high or low output indicates an impending failure event
  • Optional IEEE-1149.1 JTAG Bus interface
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Characteristic system reliability with RUL indicating prognostic distance

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