A radiation-hardened-by-design (RHBD) technique for phase-locked loops (PLLs) has been developed for single-event transient (SET) mitigation.By presenting a novel SET-resistant complementary current limiter (CCL) and implementing it between the charge pump (CP) and the loop filter (LPF),the PLL's singleevent suscepti-bility is significantly decreased in the presence of SETs in CPs,whereas it has little impact on the loop parameters in the absence of SETs in CPs.Transistor-level simulation results show that the CCL circuit can significantly reduce the voltage perturbation on the input of the voltage-controlled oscillator (VCO) by up to 93.1% and reduce the recovery time of the PLL by up to 79.0%.Moreover,the CCL circuit can also accelerate the PLL recovery procedure from loss of lock due to phase or frequency shift,as well as a single-event strike.
A novel layout has been proposed to reduce the single event upset(SEU) vulnerability of SRAM cells.Extensive 3-D technology computer-aided design(TCAD) simulation analyses show that the proposed layout can recover the upset-state much easier than conventional layout for larger space of PMOS transistors.For the angle incidence,the proposed layout is immune from ion hit in two plans,and is more robust against SEU in other two plans than the conventional one.The ability of anti-SEU is enhanced by at least 33% while the area cost reduced by 47%.Consequently,the layout strategy proposed can gain both reliability and area cost benefit simultaneously.
Since single event transient pulse quenching can reduce the SET(single event transient) pulsewidths effectively,the charge collected by passive device should be maximized in order to minimize the propagated SET.From the perspective of the layout and circuit design,the SET pulsewidths can be greatly inhibited by minimizing the layout spacing and signal propagation delay,which sheds new light on the radiation-hardened ICs(integrated circuits) design.Studies show that the SET pulsewidths of propagation are not in direct proportion to the LET(linear energy transfer) of incident particles,thus the defining of the LET threshold should be noted when SET/SEU(single event upset) occurs for the radiation-hardened design.The capability of anti-radiation meets the demand when LET is high but some soft errors may occur when LET is low.Therefore,radiation experiments should be focused on evaluating the LET that demonstrates the worst response to the circuit.
QIN JunRui CHEN ShuMing LIU BiWei CHEN JianJun LIANG Bin LIU Zheng
It has been shown that charge pumps(CPs)dominate singleevent transient(SET)responses of phase-locked loops(PLLs).Using a pulse to represent a single event hit on CPs,the SET analysis model is established and the characteristics of SET generation and propagation in PLLs are revealed.An analysis of single event transients in PLLs demonstrates that the settling time of the voltage-controlled oscillators(VCOs)control voltage after a single event strike is strongly dependent on the peak control voltage deviation,the SET pulse width,and the settling time constant.And the peak control voltage disturbance decreases with the SET strength or the filter resistance.Further-more,the analysis in the proposed PLL model is confirmed by simulation results using MATLAB and HSPICE,respectively.
In this paper,we proposed a new n-channel MOS single event transient(SET) mitigation technique,which is called the open guard transistor(OGT) technique.This hardening scheme is compared with several classical n-channel MOS hardening structures through 3-D TCAD simulations.The results show that this scheme presents about 35% improvements over the unhardened scheme for mitigating the SET pulse,and its upgrade,the 2-fringe scheme,takes on even more than 50% improvements over the unhardened one.This makes significant sense for the semi-conductor device reliability.
