Incrementally programmable non-volatile memory

摘要

An array of programmable non-volatile devices, such as a nominal OTP cell, is adapted such that a Vt representing a particular binary logic state can be changed over time. This allows for re-programming and emulating a few times or multi-time programmable device.

主权项

1. A programmable non-volatile device having at least a first programmed state and a second unprogrammed state which can be varied in time and comprising:
a programming control circuit configured to generate a programming voltage; a control gate configured to apply said programming voltage from said programming control circuit to the device; wherein said programming voltage includes at least a first voltage value and a second higher voltage value; a floating gate coupled to the control gate and adapted to store a first charge amount corresponding to said first programmed state in response to said programming voltage including said first voltage value being applied at a first programming time; said floating gate being further adapted to store a second charge amount that also corresponds to said first programmed state in response to said programming voltage including said second voltage value being applied at a second programming time; wherein said programming control circuit is further configured to perform a reset operation which sets said floating gate to a reference state in which at least said first charge amount is stored on said floating gate prior to setting such gate to store said second charge amount at said second programming time; further wherein the device does not include an electrical based erase circuit which removes electric charge from said floating gate for erase operations and is adapted to store a first unique binary programmed state (1 or 0) at different times using both a first threshold value and a second separate threshold value set for the device.