CMOS SRAM test based on quiescent supply current in write operation

A large quiescent supply current of mA order flows when a data is written in a CMOS SRAM IC. In this paper, we discuss whether faulty CMOS SRAM ICs, which can not produce the expected outputs, can be detected by measuring quiescent supply currents generated in write operations instead of output logic values. A fault detection method based on the supply current is proposed and is evaluated by some experiments. The method detects 62% of the faulty CMOS SRAM ICs used in the experiments with a small number of test inputs. Also, the total test time can be reduced if the method is used as a pretest method of functional testing. These results suggest that faulty CMOS SRAM ICs can be detected by measuring the supply currents in write operations.