Advanced Radiation Tolerant CMOS oscillators

Oscillators are the main building blocks for frequency generation and are widely used in communication systems and time-based signal processing. In applications such as spacecrafts and satellites, high-energy physics experiments like LHC and FCC and nuclear instrumentation such as in the ITER fusion reactor, large amounts of ionizing radiation can cause sudden phase and frequency errors in the oscillator due to charges deposited by the particles. In practice, 2 prominent and fundamentally limiting effects are observed in LC-oscillators: Time-dependent Single-Event Phase Transients (SEPT) and (recently discovered) temporal Single-Event Frequency Transients (SEFT) which originate in the inductor.Classically, the oscillator’s capacitance is increased to reduce its sensitivity to Single-Event Phase Transients (SEPT) at the cost of a larger power consumption. However, the phase excursion is time variant. The first main goal is to exploit this time variance and to spread the charge collection across one or multiple oscillation periods to cancel the accumulated phase errors. SEEs have usually been considered in MOS transistors resulting in phase errors. Recently, a secondary and dominant mechanism was discovered that is caused by charges in the oxides (SiO2) surrounding the spiral inductor that cause Single-Event Frequency Transients (SEFT). The second goal of the project is to further investigate this mechanism and analyze the design tradeoffs for reducing its sensitivity.

Keywords:Oscillator, Single-Event Effect, Radiation Hardening, CMOS, Radiation Effects

Disciplines:Analogue, RF and mixed signal integrated circuits, Semiconductor devices, nanoelectronics and technology, Electronic circuit and system reliability