Patent ID: 8223575
Filing Date: 2012-07-17
Classification: G11C,H01L

Abstract:
1. A multi-level electrical fuse system comprising: at least one fuse box having: at least one electrical fuse; a programming device serially coupled to the electrical fuse; a variable power supply coupled to the fuse box 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.