20-Mb/s erase/record flash memory by asymmetrical operation

The high density and low power of a flash memory makes it attractive for use as a temporary file memory of moving-pictures in future personal HDTV movie cameras with MPEG2 encoders. In this application, the recorded images are likely to be down-loaded to a permanent file within a month, and the total number of times each memory card is used will probably be less than 10/sup 4/. However, the target recording rate of 20 Mb/s is one order faster than that of the conventional flash memory. This paper, therefore, proposes high-speed erase/record circuit technologies based on asymmetrical operation, in which Vthi is set below the threshold voltage of the recording state. This scheme with accurate fast bit control, continuous record operation, and multi-phase word driving, makes 20 Mb/s erase/record flash memories attainable.