Design of radiation hardened wide tuning range CMOS oscillators

CMOS integrated circuits are prone to hazards such as Single Event Transients (SETs) caused by radiation strikes in high energy radiation environments. For synthesis of high frequency signals for circuits used in such environments, we propose use of quadrature phase LC oscillators. In addition to providing higher tolerance to SETs, these oscillators are also able to provide wider tuning range, which is otherwise difficult to achieve for high frequencies, particularly with low phase noise LC oscillators. Further improvement in the radiation tolerance is provided by addition of parallel capacitors and series resistors in tail current path. Simulation results shown 64% reduction in worst case phase offsets caused by radiation strikes generating 100 fC charge and about 20% improvement in tuning range for 14 GHz LC oscillators.