Radiation-hardened programmable two-phase clock generator

Recently, a radiation-hardened field programmable gate array with a triple modular redundant design and a two-phase clock distribution has been developed. With its triple modular redundant design and two-phase clock distribution, the radiation-hardened field programmable gate array can withstand a 730 Mrad total-ionizing dose, demonstrating tolerance of about 730 times higher than that of typically available radiation-hardened very large scale integrated circuits. However, this radiation-hardened field programmable gate array requires the distribution of three master clock signals and three slave clock signals. Moreover, a clock skew margin between the master clock signals and slave clock signals should be adjusted according to the total-ionizing dose: it requires a clock-skew adjustable clock generator. Therefore, this paper proposes a new radiation-hardened programmable two-phase clock generator for adjustment of the clock skew margin. After fabrication of the new radiation-hardened programmable two-phase clock generator, real radiation testing was done. The very large scale integrated circuit chip radiation tolerance was greater than 400 Mrad.