Dynamic sense current supply circuit and associated method for reading and characterizing a resistive memory array
View Patent ↗A dynamic sense current supply circuit and an associated method for rapidly characterizing a resistive memory array is disclosed. In one embodiment, the disclosed circuit comprises a first and second dynamically programmable current mirror sub-circuit. Responsive to a bank of control signals, each dynamically programmable current mirror sub-circuit provides a dynamically adjustable current scaling factor. These scaling factors are used to scale a supplied reference current to generate a plurality of sense currents which can be used within a plurality of read operations on a resistive memory array. A digital circuit is also provided to sense and store the result of each read operation.
1. An electronic circuit for characterizing a resistive memory array, said circuit comprising:
a first current mirror sub-circuit, said first current mirror sub-circuit comprising a first stage and a second stage, said second stage comprising at least two current branches and wherein at least one of said current branches is responsive to an enable control;
a second current mirror sub-circuit, said second current mirror sub-circuit comprising a first stage and a second stage, said second stage comprising at least two current branches and wherein at least one of said current branches is responsive to an enable control;
a reference current terminal to apply an external reference current to said first current mirror sub-circuit to generate a first current through said first current mirror sub-circuit;
an interconnection to couple said first current to said second current mirror sub-circuit;
a sense current terminal to apply a sense current passed through said second current mirror sub-circuit to a memory cell under test; and
a digital circuit element to generate a digital signal indicative of electrical current flowing through said memory cell under test.
2. The circuit of claim 1 wherein at least one of the first and second current mirror sub-circuits are substantially comprised of field effect transistors, each of said field effect transistors having a gate area ratio.
3. The circuit of claim 2 , wherein each field effect transistor has the same gate area ratio.
4. The circuit of claim 2 , wherein at least one field effect transistor has a different gate area ratio.
5. The circuit of claim 2 , wherein each field effect transistor has a different gate area ratio.
6. The circuit of claim 1 , wherein said second stage of each of said first current mirror sub-circuit and said second current mirror sub-circuit comprises three current branches.
7. The circuit of claim 2 wherein said gate area ratios within said field effect transistors comprising at least one of said first and second current mirror sub-circuits are selected to provide a desired current scaling factor through at least one of said first and second current mirror sub-circuits.
8. The circuit of claim 1 wherein at least one of said first and second current mirror sub-circuits provides at least one programmable current scaling factor through at least one of said first and second current mirror sub-circuits.
9. The circuit of claim 8 wherein the at least one programmable current scaling factor is responsive to at least one digital enable control signal.
10. The circuit of claim 1 wherein said interconnection is a current mirror circuit.
11. The circuit of claim 1 wherein said digital circuit element is comprised of at least one digital logic gate.
12. The circuit of claim 11 wherein said digital circuit element is comprised of at least one inverter.
13. The circuit of claim 1 further comprising at least one additional current mirror sub-circuit.
14. The circuit of claim 13 , wherein said at least one additional current mirror sub-circuit provides at least one additional current scale factor.