Design of auto-store circuit for nvSRAM with SONOS access transistor. (April 2023)

• Record Type: Journal Article
• Authors: Ko, Woonsan; Sung, Jaeyoung; Jeong, Junkyo; Ahn, Jaehyuk; Lee, Hideok; Lee, Gawon
• Is Part Of: Solid-state electronics. Volume 202(2023)
• Publication Date: 2023-04
• Subjects: nvSRAM -- Auto store -- Restore -- Pre-charge -- Parallel capacitor -- Series capacitor; Semiconductors -- Periodicals; Semiconducteurs -- Périodiques; 621.38152
• DOI: 10.1016/j.sse.2023.108588
• Languages: English
• ISSNs: 0038-1101

Abstract

Highlights: In this paper, the circuit that can perform store and restore operation of nvSRAM is designed. The suggested auto store circuit is consisted by two small circuit parts (store circuit and restore circuit). The nvSRAM replaced its access transistors to flash memory needs higher voltage for store operation. It demands much energy and additional voltage source to store a data. Besides restore process is also needed when it recalls the data to SRAM part. The suggested store and restore circuit charges their capacitors when power is supplied. When the power is off, the store circuit discharges its capacitors and applies higher voltage to word line for the store operation. And when the power is supplied again, the restore circuit discharges its capacitor and applies pre-charge voltage and restore voltage to bit line and word line for the restore operation. The Auto store circuit does not need additional voltage source because it shares source with nvSRAM and can perform the store, restore operation in sudden power off. Abstract: In this paper, an auto-store circuit that can perform a store and restore operation of non-volatile SRAM (nvSRAM) with access transistor whose gate stack is Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) is designed. The suggested auto-store circuit is consisted by two small circuit parts of a store and restore circuit. The store circuit moves data in SRAM cell into SONOS device before power turns off while a restore circuit recalls the data to SRAM cell when the power is resupplied. When the nvSRAM replaces its conventional access transistor with the SONOS flash memory device, higher word line voltage is needed for a store operation. It demands much energy and additional voltage source to store a data. To overcome this disadvantage, the capacitor component is added in the store and restore circuit which is charged during the normal operation mode. At the moment of the power-off, the store circuit discharges the capacitors and applies higher voltage to the word line for the store operation. When the power is supplied again, the restore circuit discharges the capacitor and applies pre-charge voltage and restore the data to the bit line and word line. The simulation results show that the suggested auto store circuit can perform the store, restore operation in the sudden power off without an additional voltage source.