Sensing circuit of memory device and associated sensing method

1. A sensing circuit of a memory device, comprising:

a cell, coupled to a first node, wherein the cell is a NAND cell or a NOR cell;

a first transistor;

a compensation source capable of providing a compensating current to the first node during a read cycle; and

a sensing module coupled to the first node, comprising:

a second transistor, wherein a first source/drain terminal of the second transistor is coupled to a second node, a second source/drain terminal of the second transistor is coupled to a ground terminal, and a gate terminal of the second transistor is coupled to a third node;

a third transistor, wherein a first source/drain terminal of the third transistor is coupled to the first node, a second source/drain terminal of the third transistor is coupled to the third node, and a gate terminal of the third transistor receives a second control signal;

wherein the cell is capable of generating a cell current during the read cycle, and the sensing module determines that the cell is in a first storing state or a second storing state in response to a relationship between the compensating current and the cell current.

2. The sensing circuit as claimed in claim 1 , wherein the cell is a single-level cell.

3. The sensing circuit as claimed in claim 2 , wherein a magnitude of the compensating current is less than a first cell current generated by the single-level cell in a first storing state, and the magnitude of the compensating current is greater than a second cell current generated by the single-level cell in a second storing state.

4. The sensing circuit as claimed in claim 3 , wherein the sensing module determines that the cell is in the first storing state when a voltage of the first node is maintained at a supply voltage, and the sensing module determines that the cell is in the second storing state when the voltage of the first node is discharged to a ground voltage.

5. The sensing circuit as claimed in claim 1 , wherein the cell is a multi-level cell, and the compensation source is capable of providing plural compensating currents to the first node during plural read cycles.

6. The sensing circuit as claimed in claim 1 , wherein a first source/drain terminal of the first transistor is coupled to the first node, a second source/drain terminal of the first transistor is coupled to a first terminal of the cell, a gate terminal of the first transistor receives a first control signal, a second terminal of the cell is coupled to the ground terminal, and a control terminal of the cell receives a word line signal.

7. The sensing circuit as claimed in claim 1 , wherein the compensation source is an adjustable current source coupled between a supply terminal and the first node.

8. The sensing circuit as claimed in claim 7 , wherein the sensing module further comprises:

a fourth transistor, wherein a first source/drain terminal of the fourth transistor is coupled to the supply terminal, a second source/drain terminal of the fourth transistor is coupled to the third node, and a gate terminal of the fourth transistor receives a third control signal;

a capacitor, wherein a first terminal of the capacitor is coupled to the third node, and a second terminal of the capacitor is coupled to the ground terminal;

a fifth transistor, wherein a first source/drain terminal of the fifth transistor is coupled to the second node, a second source/drain terminal of the fifth transistor is coupled to a fourth node, and a gate terminal of the fifth transistor receives a fourth control signal; and

a latch coupled to the fourth node.

9. A sensing method applied to a sensing circuit including a compensation source coupled a first node, wherein the sensing method comprises steps of:

activating a word line signal of a cell and controlling the cell coupled to the first node during a read cycle, wherein the cell is a NAND cell or a NOR cell;

during a first phase of the read cycle, precharging the first node to a supply voltage;

during a second phase of the read cycle, activating the compensation source for providing a compensating current to the first node, so that the first node starts to discharge;

during a third phase of the read cycle, coupling a second node with the first node, so that the second node shares charges with the first node; and

during a fourth phase of the read cycle, generating a data in response to a voltage of the second node.

10. The sensing method as claimed in claim 9 , wherein during the fourth phase, first transistor is controlled by the voltage of the second node, wherein the voltage of a third node is discharged to a ground voltage if the first transistor is turned on, and the voltage of the third node is not discharged to the ground voltage if the first transistor is turned off.

11. The sensing method as claimed in claim 10 , further comprising steps of:

determining that the cell is in the first storing state if the voltage of the third node is discharged to the ground voltage; and

determining that the cell is in the second storing state if the voltage of the third node is not discharged to the ground voltage.