Research On Soft Error Protection In Transistor And Logic Level Of Digital Circuits

With the development of technology, feature size of integrated circuit is much smaller, which means the quantity of critical charge is much less. So the IC circuit is more vulnerable to external affect. There exist energetic particles which have strong effect on the reliability of IC circuit no matter in the universe or the atmosphere we live. Energetic particle hits sensitive region of integrated circuit, making the protons ionize to electrons and holes. Ionization effect produces high-density electron-hole pairs, thus affecting the stability of IC circuit. Errors caused by radiation are divided into soft errors and hard errors. Hard errors is permanent damage while soft errors are transient and do not damage the circuit structure. Therefore, this paper mainly studies the soft error mechanism and its protection schemes.Firstly, we discuss the mechanism of soft error and study several soft error reinforcement methods in transistor and logic level. Then, a novel anti-radiation flip-flop is proposed whose name is Switching Pulse Harden Flip-Flop Based on Redundancy. After circuit simulation the pulse flip-flop is proven with a good fault tolerance. Finally, a shift register consists of Switching Pulse Harden Flip-Flop Based on Redundancy is made to a chip in order to verify its performance against soft error. And a shift register consists of standard cell is made for comparison. These two chips were subjected to basic functional tests and radiation experiments to verify its fault tolerance.Innovation of this paper is the proposition of Switching Pulse Harden Flip-Flop Based on Redundancy. Firstly, we design a new pulse flip-flop in which data capture occurs only in a very short time. The reason why we use pulse flip-flop is that pulse flip-flop only use one clock, which means a lot reduction of clock load. On the basis of this pulse flip-flop, the Switching Pulse Harden Flip-Flop Based on Redundancy is proposed by increasing some redundant circuit and a C-cell.The inadequacies of this paper is that only the basic functions experiment is implemented, while irradiation experiment is not done due to the lack of condition. However, a good resistance to radiation can be verified from the principle analysis and circuit simulation results.This Switching Pulse Harden Flip-Flop Based on Redundancy has a good fault tolerance with some area cost. Compared to standard cell, its area increased by 69%, and it costs more power. But it’s worthy for the circuit needs high reliability. Compared with conventional ways, this method costs less area and does not waste extra time, so it may be work.