A low-power SRAM using hierarchical bit line and local sense amplifiers

Abstract

This paper proposes a low power SRAM using hierarchical bit line and local sense amplifiers (HBLSA-SRAM). It reduces both capacitance and write swing voltage of bit lines by using the hierarchical bit line composed of a bit line and sub-bit lines with local sense amplifiers. The HBLSA-SRAM reduces the write power consumption in bit lines without noise margin degradation by applying a low swing signal to the high capacitive bit line and by applying a full swing signal to the low capacitive sub-bit line. The HBLSA-SRAM reduces the swing voltage of bit lines to V-DD/10 for both read and write. It saves 34% of the write power compared to the conventional SRAM. An SRAM chip with 8 K x 32 bits is fabricated in a 0.25-mu m CMOS process. It consumes 26 mW read power and 28 mW write power at 200 MHz with 2.5 V.