Nwise and Pwise: 10T Radiation Hardened SRAM Cells for Space Applications With High Reliability Requirements

Abstract

SRAM cells are widely used to design memory blocks of, e.g., caches, register files, and translation lookaside buffers. Depending on the SRAM application, the design requirements are different. For instance, in space applications, alongside energy efficiency, reliability is a main issue since the system is launched into space with a limited energy budget and stay exposed to high doses of radiation strikes for a long time. The Nwise cell has recently been proposed by the authors of this paper as the first highly reliable radiation hardened SRAM cell designed with 28nm FD-SOI. In this paper, inspired from the Nwise cell, we introduce another highly reliable radiation hardened SRAM cell, the Pwise cell, which is also designed with 28nm FD-SOI technology. Through comprehensive simulations of state-of-the-art cells, we show that both the Nwise and Pwise cells are competitive radiation hardened SRAMs to use in different memory blocks for space applications: (1) Both have the highest level of Single Event Upsets (SEU) tolerance capability for the temperature range deployed in space applications; further, both have the highest level of the tolerance capability to Multi Event Upsets (MEU). ( 2) Compared with the simulated cells that have comparable tolerance capability, the Nwise cell has low read delay and read power consumption, hence, it can be a good choice for space application cache designs, while the Pwise cell can be a proper candidate for space application register file designs since it has low write and read delay.

A Novel Fault-Tolerant Logic Style with Self-Checking Capability

“…It is important that the reference methods are base models and are widely used in recent works, e.g. [24]- [26]. For our simulations, we have chosen the size of transistors in a way that the minimum PDP is achieved for the circuit.…”

System-Scenario Methodology to Design a Highly Reliable Radiation-Hardened Memory for Space Applications

“…The Nwise and Pwise cells have been recently proposed as area-efficient and highly reliable radiation-hardened SRAM cells [11,13]. However, we will go with Nwise cell in this chapter since it is a proper choice for cache designs.…”

“…The rest of the chapter is organized as follows: In Section 2, we first briefly review the Nwise cell design details [11,13]. Then, we move on to the adapted version of the Nwise cell, which can operate reliably during voltage scaling.…”

A High-Reliability 12T SRAM Radiation-Hardened Cell for Aerospace Applications

“…Therefore, redundant node reinforcement is often used to harden the design of the cells [ 7 ], and the radiation resistance of the cells is improved through redundant feedback mechanisms [ 8 , 9 ]. Over the years, various soft-error-recovery SRAM cells have been proposed [ 6 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. The authors of [ 10 ] presented two SRAM-hardened cells, NS10T, and PS10T.…”

“…Moreover, neither of these cells can recover from a “0”→“1” SEU if sufficient charge is accumulated at the “0”-storing storage node. In addition, some hardened structures have certain soft error recovery effects, such as Nwise-10T [ 13 ], SARP-12T [ 14 ], QCCS-12T [ 15 ], RHMC-12T [ 16 ], RH-14T [ 17 ], RHS-14T [ 18 ], etc. Although the hardened cells have achieved certain radiation tolerance, most structures also suffer from sacrificing area, increasing power consumption, circuit complexity, and reduced stability, failing to achieve a good balance in terms of area, power consumption, read and write time, and radiation tolerance ability.…”