Patent ID: 8619488
Filing Date: 2013-12-31
Classification: G11C,H01L

Abstract:
1. A method for programming an electrical fuse into one of multiple states in a multi-level electrical fuse system, comprising: providing at least one electrical fuse; and providing one of multiple fuse writing voltages to the electrical fuse to program the at least one electrical fuse to one of multiple resistance states, the multi-level electrical fuse system further comprising: a programming device serially coupled to the electrical fuse; a variable power supply coupled to electrical fuse through a multiplexer and configured to generate three or more voltage levels so that the electrical fuse can be programmed into one of three or more states; a comparator having a first input coupled to the fuse box and a second input coupled to a controllable state reference circuit; and a control circuit for turning on or off the programming device in response to an output signal from the comparator, including: a first AND gate coupled between the comparator and a flip-flop; a second AND gate receiving a strobe signal and an output signal from the flip-flop; and an address decoder receiving an address signal and an output signal from the second AND gate for turning on or off the programming device.