90 nm 32 $\times$ 32 bit Tunneling SRAM Memory Array With 0.5 ns Write Access Time, 1 ns Read Access Time and 0.5 V Operation

Abstract

Functional robustness is one of the primary challenges for embedded memories as voltage levels are scaled below 1 V. A low-power high-speed tunneling SRAM (TSRAM) memory array including sense amplifiers and pre-charge circuit blocks operating at 0.5 V is designed and simulated using available MOSIS CMOS 90 nm product design kit coupled with VerilogA models developed from this group's Si/SiGe resonant interband tunnel diode experimental data. 1 T and 3 T- 2 tunnel diode memory cell configurations were evaluated. The memory array assigns 0.5 V as a logic “1” and 0 V as a logic “0”. Dual supply voltages of 1 and 0.5 V and dual threshold voltage design are used to ensure high sensing speed concurrently with low operating and standby power. Read access time of 1 ns and write access time of 2 ns is achieved for the 3 T memory cell. Write access time can be reduced to 0.5 ns for 32 bit write operations not requiring a preceding read operation. Standby power dissipation of 6×10-5 mW per cell and dynamic power dissipation of 1.8×10-7 mW/MHz per cell is obtained from the TSRAM memory array. This is the first report of TSRAM performance at the array level.