Autonomous antifuse cell
AssigneeAtmel Corporation
InventorsVincent Gosmain, Florent Garcia
Life of this patent
Estimating the term…
Abstract
An autonomous antifuse cell providing protection against intruders includes an antifuse, sense circuitry, feedback circuitry, program circuitry, and blocking circuitry. The blocking circuitry blocks access of any programming voltage input signals to the antifuse device if the antifuse is previously blown and when power is applied to the cell. In an exemplary embodiment, the antifuse cell uses only a single external access pin. Once the antifuse device is blown and during subsequent power-up operations, intrusion is prevented.
Claims13
An autonomous antifuse cell, comprising:
- an antifuse device having a ground terminal configured to be coupled to a ground voltage and a sensed terminal;
- a pass transistor configured to couple a programming voltage to the sensed terminal of the antifuse device;
- a level shifter having an output terminal coupled to a control terminal of the pass transistor, the level shifter configured to provide either conduction of the pass transistor in a write mode to program the antifuse device, or alternatively to provide conduction of a transmission gate in a read mode;
- and
- a feedback circuit having an output terminal coupled to a control input terminal of the level shifter and configured to produce a first output state to control the level shifter to be in the write mode and a second output state to control the level shifter to be in the read mode.
A method of protecting an antifuse cell from intrusion, comprising:
- providing an antifuse device having a sensed terminal;
- selectively coupling a pass transistor between a programming voltage and the sensed terminal of the antifuse device thereby programming the antifuse device with the programming voltage;
- sensing a state of the antifuse cell with a sense circuit;
- providing alternative control signals for placing the antifuse cell in either a programming state or a read state;
- placing the antifuse cell either in a write mode by controlling conduction in the pass transistor to program the antifuse device, or alternatively placing the antifuse cell in a read mode by controlling conduction of a transmission gate;
- and
- producing an output signal from a feedback circuit having a first output state to control a level shifter to be in the write mode to program the antifuse device and having a second output state for controlling the level shifter to be in the read mode.
An autonomous antifuse cell, comprising:
- an antifuse means having a ground terminal for coupling to a ground voltage and a sensed terminal;
- a voltage passing means for coupling a programming voltage to the sensed terminal of the antifuse means;
- a level shifting means for providing either conduction of the voltage passing means for programming the antifuse means in a write mode, or alternatively for providing conduction of a transmission gate in a read mode;
- and
- a feedback means for producing a first output state controlling the level shifting means to be in the write mode and a second output state controlling the level shifting means to be in the read mode.
Dependencies are inferred from the claim text.