Abstract: A method and structure for implementing a reprogrammable read only memory (ROM), and a design structure on which the subject circuit resides are provided. A pair of fuse elements having different lengths are selectively arranged to define an initial bit state. A group of a plurality of the pairs of fuse elements defines a predetermined data pattern of ones and zeros, providing initial states stored in the reprogrammable ROM. The reprogrammable ROM is reprogrammed when needed by selectively blowing a selected fuse or selected fuses to change the data pattern stored in the ROM.

Abstract: A method and structure implementing a reprogrammable read only memory (ROM) include a pair of fuse elements having different lengths and selectively arranged to define an initial bit state. A group of a plurality of the pairs of fuse elements defines a predetermined data pattern of ones and zeros, providing initial states stored in the reprogrammable ROM. The reprogrammable ROM is reprogrammed when needed by selectively blowing a selected fuse or selected fuses to change the data pattern stored in the ROM.

Abstract: An eFuse reference cell on a chip provides a reference voltage that is greater than a maximum voltage produced by an eFuse cell having an unblown eFuse on the chip but less than a minimum voltage produced by an eFuse cell having a blown eFuse on the chip. A reference current flows through a resistor and an unblown eFuse in the eFuse reference cell, producing the reference voltage. The reference voltage is used to create a mirrored copy of the reference current in the eFuse cell. The mirrored copy of the reference current flows through an eFuse in the eFuse cell. A comparator receives the reference voltage and the voltage produced by the eFuse cell. The comparator produces an output logic level responsive to the voltage produced by the eFuse cell compared to the reference voltage.