Patent attributes
An electrically programmable fuse includes a metal-oxide-semiconductor (MOS) programmable transistor that is gate-source coupled by a resistive element. The resistive element can comprise a gate-source coupled MOS transistor. If the MOS transistor is unprogrammed, then the resistive element ensures that the programmable transistor is turned off during read operations. However, when a programming voltage is applied across the source and drain terminals of the programmable transistor, the resistive element allows the programming voltage to be capacitively coupled to the gate of the programmable transistor from its drain. This turns the programmable transistor on, thereby reducing the snapback voltage of the programmable transistor, and hence, the required programming voltage. Once the snapback mode is entered, current flow through the programmable transistor increases until thermal breakdown occurs and the programmable transistor shorts out. The programmable transistor will then behave as a constant-on transistor during all subsequent read operations.
