Properties and Design of CMOS Thyristor Delay Elements

The CMOS thyristor delay element and its basic operation are presented in this paper. Six variations of the thyristor design developed over the years to extend the delay length, to improve the consistency of the delay, or to control the sensitivities of the delay are also discussed. This includes the complementary thyristor, the thyristor without the current source, the thyristor with threshold elevation, the thyristor with opposing current source, the single-ended thyristor, and the thyristor-type feedback delay element. Design considerations common to all CMOS thyristors are also discussed to provide insights on topology selection, capacitive loading, and transistor sizing.