A PLL for clock generation with automatic frequency control under TID effects

This paper presents a PLL scheme for clock generation with a Total Ionizing Dose (TID) degradation detector. Externally to the PLL circuitry, when the degradation due to TID effects reaches a certain predefined threshold, the circuit reduces the clock frequency output. To compensate for the increased delay caused by the total dose effect (TID), the system increases the clock period in order to avoid timing violations, increasing the chip lifespan. The circuit was designed in a 0.35μm CMOS process and simulated with HSPICE tool.