Multiple-state one-time programmable (OTP) memory to function as multi-time programmable (MTP) memory
A circuit, method, and system for using multiple-state One-Time Programmable (OTP) memory to function as a multiple-bit programmable (MTP) memory. The OTP memory can have N (N>2) distinct resistance states, that can be differentiated by at least N−1 reference resistances, can be functionally equivalent programmed N−1 times. The multiple-state OTP memory can have a plural of multiple-state OTP cells that can be selectively programmed to a resistance state. The reference resistance can be set to determine a state of the from the programmed multiple-state OTP cells.
1. A multiple-state One-Time Programmable (OTP) memory, comprising:
a plurality of multiple-state One-Time Programmable (OTP) memory cells, at least one of the multiple-state One-Time Programmable (OTP) memory cells having an One-Time Programmable (OTP) element with N (N>2) distinct resistance states from R(0), R(1), . . . , to R(N−1), wherein R(0) being the virgin state;
a program control circuit to apply high voltage or high current pulses to program the One-Time Programmable (OTP) cells; and
a sensing circuit with at least N−1 reference resistance levels to sense the One-Time Programmable (OTP) cell into digital data, and
wherein the One-Time Programmable (OTP) memory being configured to function as an N−1 time programmable memory by programming the One-Time Programmable (OTP) cells that have data 1s into the R(1) state the first time, by programming the One-Time Programmable (OTP) cells that have data 1s into the R(2) state the second time, until by programming the One-Time Programmable (OTP) cells that have data 1s into the R(N−1) state the N−1 time.
2. A multiple-state One-Time Programmable (OTP) memory as recited in claim 1 , wherein the One-Time Programmable (OTP) element is an electrical fuse.
3. A multiple-state One-Time Programmable (OTP) memory as recited in claim 2 , wherein the One-Time Programmable (OTP) element has at least a portion of polysilicon, silicided polysilicon, heat-isolated active region, local interconnect, metal, or metal alloy.
4. A multiple-state One-Time Programmable (OTP) memory as recited in claim 2 , wherein the One-Time Programmable (OTP) element is constructed from a portion of CMOS gates.
5. A multiple-state One-Time Programmable (OTP) memory as recited in claim 1 , wherein the One-Time Programmable (OTP) memory is configured to be programmed into the desirable resistance states by repetitively turning on the program control circuit to program the multiple-state One-Time Programmable (OTP) cells, and the sensing circuit to verify the data until the desirable resistance state is reached.
6. A multiple-state One-Time Programmable (OTP) memory as recited in claim 5 , wherein the magnitude, duration, or the number of the program pulses to program into different resistance states are not the same.
7. A multiple-state One-Time Programmable (OTP) memory as recited in claim 1 , wherein the program control circuit has at least one register to store programming time count.
8. A multiple-state One-Time Programmable (OTP) memory as recited in claim 7 , wherein the programming time count register is nonvolatile.
9. A multiple-state One-Time Programmable (OTP) OTP memory as recited in claim 7 , wherein the program control circuit sets proper reference resistance for the sensing circuit based on programming time count register.
10. A multiple-state One-Time Programmable (OTP) memory as recited in claim 7 , wherein the content of the programming time count register can be read to output.
11. An electronic system, comprising:
a processor; and
a multiple-state One-Time Programmable (OTP) memory operatively connected to the processor, the multiple-state One-Time Programmable (OTP) memory includes at least a plurality of multiple-state One-Time Programmable (OTP) cells for providing data storage, at least one of the multiple-state One-Time Programmable (OTP) memory cells having an One-Time Programmable (OTP) element with N (N>2) distinct resistance states from R(0), R(1), . . . , to R(N−1), wherein R(0) is a virgin state;
a program control circuit to apply high voltage or high current pulses to program the One-Time Programmable (OTP) cells; and
a sensing circuit with at least N−1 reference resistance levels to sense the One-Time Programmable (OTP) cell into digital data,
wherein the multiple-state One-Time Programmable (OTP) memory being configured to function as an N−1 time programmable memory by programming the multiple-state One-Time Programmable (OTP) cells that have data 1s into the R(1) state the first time, by programming the multiple-state One-Time Programmable (OTP) cells that have data 1s into the R(2) state the second time, until by programming the multiple-state One-Time Programmable (OTP) cells that have data 1s into the R(N−1) state the N−1 time.
12. An electronic system as recited in claim 11 , wherein the multiple-state One-Time Programmable (OTP) cell has an electrical fuse.
13. An electronic system as recited in claim 12 , wherein the multiple-state One-Time Programmable (OTP) cell has at least a portion of polysilicon, silicided polysilicon, heat-isolated active region, local interconnect, metal, or metal alloy.
14. An electronic system as recited in claim 12 , wherein the multiple-state One-Time Programmable (OTP) cell has an interconnect constructed from a CMOS gate.
15. An electronic system as recited in claim 11 , wherein the multiple-state One-Time Programmable (OTP) cell is configured to be programmed into the desirable resistance states by repetitively turning on the program control circuit to program the multiple-state One-Time Programmable (OTP) cells, and the sensing circuit to verify the data until the desirable resistance state is reached.
16. An electronic system as recited in claim 15 , wherein the magnitude, duration, or the number of the program pulses to program into different resistance states are not the same.
17. An electronic system as recited in claim 11 , wherein the program control circuit has at least one register to store programming time count.
18. A method for providing a multiple-time programmable memory from a multiple-state One-Time Programmable (OTP) memory, comprising:
providing a plurality of multiple-state One-Time Programmable (OTP) cells, at least one of the multiple-state One-Time Programmable (OTP) cells includes at least (i) an One-Time Programmable (OTP) element has N (N>2) distinct resistance states; (ii) a program control circuit to apply high voltage or high current pulses to program the multiple-state One-Time Programmable (OTP) cells; and (iii) a sensing circuit with at least N−1 reference resistance levels to sense the multiple-state One-Time Programmable (OTP) cell into digital data,
wherein the multiple-state One-Time Programmable (OTP) memory being configured to function as an N−1 time programmable memory by programming the multiple-state One-Time Programmable (OTP) cells that have data 1s into the R(1) state the first time, by programming the One-Time Programmable (OTP) cells that have data 1s into the R(2) state the second time, until by programming the One-Time Programmable (OTP) cells that have data 1s into the R(N−1) state the N−1 time.
19. A method to program multiple-state One-Time Programmable (OTP) memory as recited in claim 18 , wherein the multiple-state One-Time Programmable (OTP) memory being configured to program into the desirable resistance state by repetitively turning on the program control circuit to program the multi-state One-Time Programmable (OTP) cells, and wherein the sensing circuit is configured to verify the data until the desirable resistance state is reached.
20. A method to read multiple-state One-Time Programmable (OTP) memory as recited in claim 18 , wherein the program control circuit has a programming time count register to store the programming time count.