The severity of power consumption during parallel BIST of embedded memory
cores is growing significantly. In order to alleviate this problem, a row bank-based precharge
technique based on the divided wordline (DWL) architecture is proposed for low-power testing of embedded
SRAMs. The memory cell array is first divided into row banks. The effectiveness of the row
bank-based precharge technique is due to the predictable address sequence during test. In low-power test
mode, instead of precharging the entire memory array, only the current accessed row bank is
precharged. This will result in significant power saving for the precharge circuitry. The precharge power
can be reduced to 1/b of that of the traditional precharge techniques, where b denotes the number of row banks in the memory array. With simple transmission
gates and inverters, the modified precharge control circuitry was also designed. The hardware
overhead for implementing the low-power technique is almost negligible. Moreover, the corresponding
BIST design to implement the low-power technique is almost the same as the conventional BIST
designs. It is also notable that the inherent low-power characteristics of the DWL architecture can
be preserved. According to experimental results, 48.9% power reduction can be achieved for
a 256 × 256 bit-oriented SRAM. The memory is divided into 8 row banks. Moreover, if the number of
row banks increases, the power saving will also increase.
