Semiconductor device and DRAM controller
View Patent ↗According to a semiconductor device of the present invention, a differential potential between a sense amplification level and a precharge level of a sense amplifier is set to a power supply potential (VCC-GND) so as to improve resistance against degradation of hold characteristics. Further, low power consumption can be realized along with the improvement. Additionally, the precharge level is set to a power supply of GND or VCC so as to realize a stable supply of the precharge level. Further, a chip size can be reduced since a power supply circuit for precharge is not needed.
1. A semiconductor device, comprising:
a DRAM cell;
a sense amplifier to which a power supply pair is input, the power supply pair including a first power supply and a second power supply;
a power supply circuit to which a power supply voltage and a ground voltage are input; and
a sense amplifier control circuit determining a potential of the power supply pair, wherein
the sense amplifier precharges a potential of a bit line pair to a power supply potential or a ground potential before amplifying information stored in the DRAM cell, the DRAM cell being connected to either one of the bit line pair, and
the sense amplifier control circuit controls the power supply pair so that a potential difference of the bit line pair becomes larger than a differential potential between the power supply voltage and the ground voltage when the sense amplifier performs an amplification operation.
2. The semiconductor device according to claim 1 , wherein the DRAM cell comprises:
an Nch transistor; and
a capacitor connected to the Nch transistor.
3. The semiconductor device according to claim 1 , wherein the DRAM cell comprises:
a Pch transistor; and
a capacitor connected to the Pch transistor.
4. The semiconductor device according to claim 2 , wherein
when the selected DRAM cell stores charge in the capacitor to store “1” state,
the sense amplifier amplifies a potential of one bit line of the bit line pair connected to the DRAM cell to the power supply voltage and amplifies a potential of the other bit line to a first voltage which is lower than the ground voltage.
5. The semiconductor device according to claim 3 , wherein
when the selected DRAM cell stores charge in the capacitor to store “1” state,
the sense amplifier amplifies a potential of one bit line of the bit line pair connected to the DRAM cell to the ground voltage and amplifies a potential of the other bit line to a second voltage which is higher than the power supply voltage.
6. The semiconductor device according to claim 2 , further comprising an equalizer equalizing the potential of the power supply pair and/or the potential of the bit line pair, the equalizer being formed by an Nch transistor.
7. The semiconductor device according to claim 3 , further comprising an equalizer equalizing the potential of the power supply pair and/or the potential of the bit line pair, the equalizer being formed by a Pch transistor.
8. The semiconductor device according to claim 2 , wherein
the sense amplifier control circuit further comprises a negative voltage level shifter, and
the negative voltage level shifter converts an amplitude between the power supply voltage and the ground voltage of a signal input to the sense amplifier control circuit into an amplitude between the power supply voltage and a negative voltage lower than the ground voltage.
9. The semiconductor device according to claim 3 , wherein
the sense amplifier control circuit further comprises a positive voltage level shifter, and
the positive voltage level shifter converts an amplitude between the power supply voltage and the ground voltage of a signal input to the sense amplifier control circuit into an amplitude between a positive voltage higher than the power supply voltage and the ground voltage.
10. The semiconductor device according to claim 2 , wherein a back gate voltage of the DRAM cell is lower than the ground voltage.
11. The semiconductor device according to claim 3 , wherein a back gate voltage of the DRAM cell is higher than the power supply voltage.
12. The semiconductor device according to claim 1 , wherein the power supply circuit further comprises a step-up circuit and/or a step-down circuit.
13. The semiconductor device according to claim 2 , wherein an intermediate potential between two potentials obtained by amplifying the bit line pair by the sense amplifier is input to one contact of the capacitor.
14. The semiconductor device according to claim 3 , wherein an intermediate potential between two potentials obtained by amplifying the bit line pair by the sense amplifier is input to one contact of the capacitor.
15. The semiconductor device according to claim 1 , further comprising a control circuit, the control circuit generating a sense amplifier activating signal controlling an amplification operation of the sense amplifier.
16. A semiconductor device, comprising:
a DRAM cell;
a sense circuit to which a power supply pair is input, the power supply pair including a first power supply and a second power supply;
a power supply circuit to which a power supply voltage and a ground voltage are input; and
a sense amplifier control circuit determining a potential of the power supply pair, wherein
the sense circuit precharges a potential of a bit line pair to a power supply potential or a ground potential before amplifying information stored in the DRAM cell, the DRAM cell being connected to either one of the bit line pair, and
the sense amplifier control circuit sets a potential of the first power supply to be higher than the power supply voltage or sets a potential of the second power supply to be lower than the ground voltage when the sense circuit performs an amplification operation.
17. A DRAM controller, comprising:
setting a potential of a bit line pair to a potential same to one of a power supply potential and a ground potential, the DRAM cell being connected to one of the bit line pair;
supplying selected voltage to a word line connected to the DRAM cell; and
amplifying a potential difference generated in the bit line pair to be larger than a differential potential between the power supply voltage and the ground voltage.