Dynamic type semiconductor memory device and operation method of the same

1. A dynamic type semiconductor memory device comprising:

a sense amplifier connected with a bit line pair to amplify and sense a voltage difference on said bit line pair;

a precharge circuit configured to precharge said bit line pair to a power supply voltage on a lower side in response to a first control signal;

a memory cell capacitance having one end which is connected with said bit line pair through a first switch circuit which is controlled in response to a signal on a word line; and

a reference cell capacitance having one end which is connected with said bit line pair through a second switch circuit which is controlled in response to a signal on a reference word line;

wherein the other end of said memory cell capacitance and the other end of said reference cell capacitance are electrically separated.

2. The dynamic type semiconductor memory device according to claim 1 , wherein the other end of said memory cell capacitance is fixed to a first voltage, and the other end of said reference cell capacitance is fixed to a second voltage.

3. The dynamic type semiconductor memory device according to claim 2 , wherein the second voltage is the power supply voltage on the lower side.

4. The dynamic type semiconductor memory device according to claim 2 , wherein the second voltage is a power supply voltage on a higher side.

5. The dynamic type semiconductor memory device according to claim 1 , wherein said one end of said reference cell capacitance is connected through a third switch circuit with a node to which a reference voltage is supplied, and

said third switch circuit controls a connection between said one end of said reference cell capacitance and said node in response to a second control signal.

6. The dynamic type semiconductor memory device according to claim 5 , wherein said reference voltage is an intermediate voltage between a power supply voltage on a higher side and the power supply voltage on the lower side.

7. The dynamic type semiconductor memory device according to claim 2 , wherein said first voltage is an intermediate voltage between a power supply voltage on a higher side and the power supply voltage on the lower side.

8. An operation method of a dynamic type semiconductor memory device, comprising:

precharging a bit line pair to a power supply voltage on a lower side;

supplying a reference voltage to a reference cell capacitance;

redistributing charges stored in said reference cell capacitance between said reference cell capacitance and said bit line pair in a state that one end of said reference cell capacitance and one end of a memory cell capacitance are electrically separated; and

connecting said memory cell capacitance with said bit line pair.

9. The operation method of a dynamic type semiconductor memory device according to claim 8 , further comprising:

fixing one end of said memory cell capacitance is fixed to a first voltage, and one end of said reference cell capacitance is fixed to a second voltage.

10. The operation method of a dynamic type semiconductor memory device according to claim 9 , wherein the second voltage is the power supply voltage on the lower side.

11. The operation method of a dynamic type semiconductor memory device according to claim 10 , wherein the second voltage is a power supply voltage on a higher side.

12. The operation method of a dynamic type semiconductor memory device according to claim 8 , wherein said reference voltage is an intermediate voltage between a power supply voltage on a higher side and the power supply voltage on the lower side.

13. The operation method of a dynamic type semiconductor memory device according to claim 9 , wherein said first voltage is an intermediate voltage between the power supply voltage on the higher side and the power supply voltage on the lower side.