| 摘要 |
A system and method are disclosed for providing an electrically programmable read only memory (EPROM) in which each memory cell comprises an NMOS select transistor and a PMOS program transistor with a thick gate oxide and a PMOS breakdown transistor with a thin gate oxide. The source of the NMOS transistor and the source, drain and N well of the PMOS breakdown transistor are connected. The gate of the PMOS breakdown transistor is connected to the PMOS program transistor. The memory cell is programmed by two voltage pulses that are passed to the N well of the PMOS breakdown transistor. The combined voltage of the two pulses is sufficient to break the thin gate oxide of the PMOS breakdown transistor. Because the memory state of the memory cell depends on the breakdown status of the PMOS breakdown transistor, the data may be retained in the memory cell for an unlimited period of time.
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