Radiation‐hardened read‐decoupled low‐power 12T SRAM for space applications

Abstract

In advanced technology, static random-access memory (SRAM) cells used in space are highly sensitive to charge variations caused by high-energy particle strikes, which cause soft-error. Therefore, it is imperative for an SRAM to withstand this harsh environment. However, 6T cells are unable to function reliably in such a place. In order to address this, a radiation-hardened readdecoupled 12T (RHRD12T) SRAM cell is proposed in this paper. The relative strength of RHRD12T is estimated by comparing it with other contemporary cells such as NS10T, PS10T, RHBD10T, QUATRO12T, QUCCE12T, and RHD12T on various major design metrics. Due to the read-decoupled nature of RHRD12T, it shows the highest read stability. It also consumes the lowest hold power compared to all other considered cells, except NS10T. Moreover, RHRD12T exhibits the highest write ability due to the use of two extra access transistors and the poor driving ability of the internal nodes. In terms of write delay, RHRD12T shows an improvement of 1.02Â/1.06Â/1.07Â/1.08Â over NS10T/RHD12T/PS10T/RHBD10T at V DD = 1 V. Moreover, RHRD12T is capable of tolerating the highest amount of critical charge among all other comparison cells and is the least susceptible to single-event upsets. All the aforementioned improvements are obtained at the cost of longer read delay. K E Y W O R D Sdigital circuit, low power design, memory design, read stability, SRAM | INTRODUCTIONSatellites have become an integral part of human society, as we rely on satellite communication for a wide range of services, from meteorology to disaster monitoring, from navigation systems to military operations, and so on. 1 As the technology is advancing, lightweight satellites are replacing heavyweight satellites because of their higher manufacturing cost. 2 Since lightweight satellites have limited resources, they require high-density memory cells, and static random-access memory (SRAM) cells are the best alternative for space applications because of their high packing density and improved logic performance. 1 Space presents extreme conditions, like temperature fluctuations and radiation. Due to the weak geomagnetic field in space, radiation and energized particles increase. To withstand this harsh environment, special electronic components and circuits are used. Once a radiation particle strikes a logic circuit at its sensitive node, it generates electron-hole pairs (Figure 1A). These pairs become separated and accumulate at the sensitive node. 3 The accumulated charge at the sensitive node then generates a transient voltage pulse. If enough charge (i.e., critical charge, Q C ) is

Modeling and Simulation of Low Power Single Event Upset-resilient SRAM cell

“…Radiation-induced soft errors are a threat to the basic functionality of any logic cell. Data corruption and system failures because of the inability to eliminate radiation induced soft errors might have dangerous results in mission critical systems such as mainstream servers, automobile, and spacecrafts [10][11]. With technology scaling reaching deep submicron dimensions of less than 250nm, frequency of operation reaching to 100MHz and the increased speed and complexity of around a million gates in a circuit, Single Event Transient (SET) issues became a commonly occurring problem by the end of the 90s [12].…”

A two‐dimensional RC network topology for fault‐tolerant design of analog circuits

“…However, with components now reaching molecular‐scale dimensions and power density levels ever increasing, fault tolerance has become an even more important aspect in the design of integrated circuits 1 . This is a crucial issue for devices operating under harsh environmental conditions, especially those exposed to high‐energy particles or X‐ray and gamma radiation, such as satellite and space exploration vehicles, 2 robotic systems for nuclear waste disposal, 3 and detector circuits for high‐energy physics experiments 4 . In this case, the effects may range from soft errors to full system failures after long‐term exposure 5 .…”

Soft-Error-Immune Read-Stability-Improved SRAM for Multi-Node Upset Tolerance in Space Applications

“…Error correction codes (ECCs) are a possible solution to mitigate soft-errors. However, ECCs have redundancy, and they require coding-decoding circuits, which incur a huge power, area and delay penalty [6], [7]. In view of the above issues, it is very much desired to design a soft-error-immune SRAM cell which can recover from SEUs as well as SEMNUs in the space environment [2].…”

“…Hence, the conventional 6T SRAM fails to meet the requirements of soft-error immunity. Over the years, various soft-error-immune SRAM cells have been proposed [3], [7]- [13]. The authors of [10] presented two soft-error-immune SRAM cells, NS10T and PS10T.…”

“…Furthermore, both WE-QUATRO and QUCCE12T pose an issue of poor read stability and consume high hold power. A soft-error-immune SRAM cell, named RHRD12T, with improved read stability and write ability was proposed in [7]. However, the cell cannot recover its data if enough charge is collected at the '0'-storing storage node.…”