The Radiation-harden Design Of Master-slave DLL For DDR3 SDRAM PHY

Delay-locked loop(DLL)has the advantage of accurate clock positioning,high speed locking,avoiding jitter and so on,thus it is widely used in synchronization network of high-speed memory interface and multi-phase clock generator.With the development of DDR3 SDRAM and higher speed memory,DLL plays a very significant role on the performance of DDR3 SDRAM interface circuit.The clock generator is the main part of the electronic system,in which unpredictable frequency fluctuation and phase deviation will affect the stability and reliability of the system.Therefore,the radiation harden design of the clock generator is more and more concerned.In this paper,not only the theory of delay locked loop in DDR3 SDRAM interface circuit,but also the radiation harden design of DLL is concerned,especially for single-event transient effects,single-event latch-up,single-event upset and Total Ionizing Dose effects.Based on the 65 nm CMOS process,the radiation-harden delay locked loop operates on from 100 MHz to 533 MHz for DDR3 SDRAM interface circuit.Simulation of schematic and layout results show that the delayed locked loop has the characteristics of fast locking,strong anti-interference ability and good stability.In the meanwhile,the single-event latchup threshold reaches 75MeV/ mg · cm!!,the total dose effect threshold is greater than 100krad(Si).It can be predicted that the circuit has good stability in the space.The main content of this paper is as follows:The DLL designed in this paper has a voltage-controlled charge pump which realizes the current matching.It also adds some fine-tuning module and Design for Testability to facilitate the adjustment and testing.The radiation-harden DLL is designed against single-event transient effect,single-event latch-up effect,single-particle flip effect and total dose effect.Such as phase detector with Dice D flip-flop,voltage-controlled charge pump with a compensation network,radiation harden method in the layout design are used to improve the stability of DLL in space.