A hybrid ECC and redundancy technique for reducing refresh power of DRAMs

Dynamic random access memory (DRAM) is one key component in handheld devices. It typically consumes significant portion of the energy of the device even if the device is in standby mode due to the refresh requirement. This paper proposes a hybrid error-correcting code (ECC) and redundancy (HEAR) technique to reduce the refresh power of DRAMs in standby mode. The HEAR circuit consists of a Bose-Chaudhuri-Hocquenghem (BCH) module and an error-bit repair (EBR) module to raise the error correction capability and minimize the adverse effects caused by the ECC technique such that the refresh period can be effectively prolonged and considerable refresh power reduction can be achieved. Analysis results show that the proposed HEAR scheme can achieve 40~70% of energy saving for a 2Gb DDR3 DRAM in standby mode. The area cost of parity data and ECC circuit of HEAR scheme is only about 63 % and 53 % of that of the ECC-only, respectively.