Redundant encoding for buried metal fuses

摘要

An integrated circuit has a plurality of buried metal fuses and an apparatus for selectively controlling the plurality of buried metal fuses. Each buried metal fuse has an output state. A plurality of latches each correspond to a respective one of the plurality of buried metal fuses. An encoding fuse has a first state and a second state. A plurality of gates, consists of either a plurality of XOR gates or a plurality of XNOR gates. Each gate has a first input coupled to the output of a respective one of the plurality of buried metal fuses and a second input coupled to the encoding fuse. Each gate has an output coupled to a respective one of the plurality of latches. Each of the plurality of latches has an output state that is the same as the state of the respective one of the plurality of buried metal fuses to which that latch is coupled, when the encoding fuse is in the first state. Each of the plurality of latches has an output state that is opposite the state of the respective one of the plurality of buried metal fuses to which that latch is coupled, when the encoding fuse is in the second state.