Cochran Freund & Young LLC
SRAM based one-time-programmable memory
Disclosed is a method and device for providing fast-response One-Time-Programmable (OTP) memory based on SRAM memory technology and the inherent breakdown characteristics of a MOS transistor. Each memory cell of an SRAM memory cell circuit is connected to a programming circuit. The programming circuit is comprised of two groups of MOS transistors connected to the storage nodes (SN and SNB, where SNB is the complementary value of SN) of the two cross-coupled inverters of the SRAM memory circuit. A desired data set is loaded into the circuit and then is burned-in by applying and repeatedly cycling a “burn-in” voltage across the source and drain of the MOS transistors of the programming circuit that approaches the ON STATE trigger voltage of the characteristic bipolar junction transistor contained within the MOS transistors. Upon repeated cycling of the source-to-drain voltage, the targeted MOS transistor within the programming circuit breaks down and shorts across the gate, drain, and/or source of the transistor. When the system is returned to normal operation, the programming circuits will be connected to ground, Vdd or Vss and one of the two nodes of the SRAM cell circuit will be shorted through the programming circuit to ground, Vdd or Vss, thus, forcing a retention of the programmed data state.
LSI Corporation
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inventional inventional
Ramnath Subramanian Ruggero
Venkatraman Ramesh Castagnetti