Abstract:
Background Phase-locked loops (PLL) circuit plays a significant role in microprocessor clock circuits and high-speed interface circuits. Conducting research on the strong radiation effect of PLL circuits could provide basic data for evaluating their overall damage response.
Purpose In consideration of transistors’ energy deposition fluctuation to be more close to practical radiation, the total ionizing dose (TID) effect of a typical 0.18 μm process phase-locked loops circuit (PLL) was equivalently studied, which could make up for the deficiencies of previous related research.
Methods Employing Monte Carlo sampling method to modify the sensitive parameters of the transistor SPICE model, the TID effect of PLL circuit was studied, where the statistical distributions of output frequency f, phase difference δ, and control voltage Vvco_in under different TID ranging from 0 to 200 krad (SiO2) are given.
Results Results demonstrate that the values of f and δ would be changed in various degrees under TID effect without considering the energy deposition fluctuations, and they could eventually return to normal through the circuit’s feedback mechanism. On the contrary, when considering the energy deposition fluctuations, the PLL circuit shows an unexpected frequency response after phase locking, which may lead to data loss during the communication process and disturbances to the processor’s functionality, thus leading to a disaster’s impact on the overall behavior of the circuit.
Conclusions The simulation methods and results in this paper could provide references for considering or evaluating TID effect of PLL circuits under real conditions, and further offer suggestions on the design of anti-TID effect of PLL circuits.
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