Semiconductor Device and Method of Driving Semiconductor Device

• US 20120049901A1
• Filed: 08/25/2011
• Published: 03/01/2012
• Est. Priority Date: 08/27/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Shionoiri, Yutaka, Kamata, Koichiro, Takewaki, Yoshiya
• Granted Patent: US 8,952,728 B2
• Time in Patent Office: Days
• US Class Current: 327/109
• CPC Class Codes: H03K 19/0016 by using a control or a clock signal, e.g. in order to apply power supply

Abstract

An object of the invention is to reduce the power consumption of a semiconductor device that requires a plurality of reference potentials and a method of driving the semiconductor device. Disclosed is a semiconductor device having a potential divider circuit in which a potential supplied to a power supply line is resistively divided by resistors connected in series to the power supply line so that a desired potential is output through a switch transistor electrically connected to the power supply line. A drain terminal of the switch transistor is electrically connected to a gate terminal of a transistor provided in a circuit on the output side (or to one terminal of a capacitor) to form a node. The switch transistor has an off current low enough to hold the desired voltage in the node even when the potential is no more supplied to the power supply line.

Claims

1. A semiconductor device comprising a potential divider circuit comprising:

a power supply line;

a selection line;

an operational amplifier circuit including a first transistor, the first transistor including a first gate, a first source and a first drain;

a first resistor and a second resistor, the first resistor and the second resistor being connected in series to the power supply line; and

a switch transistor comprising a gate, a source and a drain, the gate being electrically connected to the selection line, the source being electrically connected to a node between the first resistor and the second resistor, and the drain being electrically connected to the first gate of the first transistor of the operational amplifier circuit.

2. A semiconductor device comprising a potential divider circuit according to claim 1, the operational amplifier circuit comprising:

a constant current source;

a second transistor including a second gate, a second source and a second drain, the second source being electrically connected to the first source and to the constant current source;

a third transistor including a third gate, a third source and a third drain; and

a fourth transistor including a fourth gate, a fourth source and a fourth drain, the fourth gate being electrically connected to the third gate, the third drain and the first drain, the fourth source being electrically connected to the third source, and the fourth drain being electrically connected to the second drain and the second gate.

5. A semiconductor device comprising a potential divider circuit according to claim 1, further comprising a potential controller transistor configured so that the first resistor and the second resistor are electrically connected to the power supply line through a source and a drain of the potential controller transistor.

8. A semiconductor device comprising a potential divider circuit according to claim 5, wherein a gate of the potential controller transistor is electrically connected to the gate of the switch transistor.

11. A semiconductor device comprising a potential divider circuit according to claim 1, further comprising:

a potential supply source configured to supply a potential to the potential divider circuit; and

a load connected to outputs of the potential supply source and to outputs of the potential divider circuit.

14. A semiconductor device comprising a potential divider circuit according to claim 1, wherein the switch transistor includes an oxide semiconductor layer.

17. A semiconductor device comprising a potential divider circuit according to claim 1,

wherein the switch transistor and the first transistor are formed over a same substrate;

wherein the first transistor includes a first semiconductor material and is in a lower portion; and

wherein the switch transistor includes an oxide semiconductor and is in an upper portion, the upper portion being located over the lower portion.

19. A semiconductor device comprising a potential divider circuit according to claim 1,

wherein the semiconductor device is any one of a computer, a mobile phone set, a portable information terminal, a digital camera, a digital video camera, electronic paper and a television set.

3. A semiconductor device comprising a potential divider circuit comprising:

a power supply line;

a selection line;

a capacitor;

a first resistor and a second resistor connected in series to the power supply line; and

a switch transistor comprising a gate, a drain and a source, the gate being electrically connected to the selection line, the source being electrically connected to a node between the first resistor and the second resistor, and the drain being electrically connected to the capacitor.

6. A semiconductor device comprising a potential divider circuit according to claim 3, further comprising a potential controller transistor configured so that the first resistor and the second resistor are electrically connected to the power supply line through a source and a drain of the potential controller transistor.

9. A semiconductor device comprising a potential divider circuit according to claim 6, wherein a gate of the potential controller transistor is electrically connected to the gate of the switch transistor.

12. A semiconductor device comprising a potential divider circuit according to claim 3, further comprising:

a potential supply source configured to supply a potential to the potential divider circuit; and

a load connected to outputs of the potential supply source and to outputs of the potential divider circuit.

15. A semiconductor device comprising a potential divider circuit according to claim 3, wherein the switch transistor includes an oxide semiconductor layer.

20. A semiconductor device comprising a potential divider circuit according to claim 3,

wherein the semiconductor device is any one of a computer, a mobile phone set, a portable information terminal, a digital camera, a digital video camera, electronic paper and a television set.

4. A semiconductor device comprising a potential divider circuit comprising:

a power supply line;

a first transistor;

the first transistor including a first gate;

a first resistor and a second resistor, the first resistor and the second resistor being connected in series to the power supply line; and

a switch transistor comprising a gate, a source and a drain, the gate being electrically connected to the source and to a node between the first resistor and the second resistor, and the drain being electrically connected to the first gate of the first transistor.

7. A semiconductor device comprising a potential divider circuit according to claim 4, further comprising a potential controller transistor configured so that the first resistor and the second resistor are electrically connected to the power supply line through a source and a drain of the potential controller transistor.

10. A semiconductor device comprising a potential divider circuit according to claim 7, wherein a gate of the potential controller transistor is electrically connected to the gate of the switch transistor.

13. A semiconductor device comprising a potential divider circuit according to claim 4, further comprising:

a potential supply source configured to supply a potential to the potential divider circuit; and

a load connected to outputs of the potential supply source and to outputs of the potential divider circuit.

16. A semiconductor device comprising a potential divider circuit according to claim 4, wherein the switch transistor includes an oxide semiconductor layer.

18. A semiconductor device comprising a potential divider circuit according to claim 4,

wherein the switch transistor and the first transistor are formed over a same substrate;

wherein the first transistor includes a first semiconductor material in a lower portion; and

wherein the switch transistor includes an oxide semiconductor in an upper portion.

21. A semiconductor device comprising a potential divider circuit according to claim 4,

wherein the semiconductor device is any one of a computer, a mobile phone set, a portable information terminal, a digital camera, a digital video camera, electronic paper and a television set.

22. A method of driving a semiconductor device comprising a potential divider circuit comprising:

a power supply line;

a selection line;

an operational amplifier circuit including a first transistor;

the first transistor including a first gate, a first source and a first drain;

a first resistor and a second resistor, the first resistor and the second resistor being connected in series to the power supply line; and

a switch transistor comprising a gate, a source and a drain, the gate being electrically connected to the selection line, the source being electrically connected to a node between the first resistor and the second resistor, and the drain being electrically connected to the first gate of the first transistor of the operational amplifier circuit to form a second node,

the method comprising;

dividing a potential supplied to the power supply line with the first resistor and the second resistor to obtain a wished potential;

applying the wished potential to the operational amplifier circuit through the switch transistor when the switch transistor is turned on;

holding the wished potential at the second node when the switch transistor is turned off; and

outputting the wished potential from the operational amplifier circuit, the switch transistor being either turned on or turned off.

24. A method of driving a semiconductor device according to claim 22,

wherein the semiconductor device comprises a potential controller transistor configured so that the first resistor and the second resistor are electrically connected to the power supply line through a source and a drain of the potential controller transistor, and

wherein the potential controller transistor is turned off when the switch transistor is turned off.

23. A method of driving a semiconductor device comprising a potential divider circuit comprising:

a power supply line;

a selection line;

a capacitor;

a first resistor and a second resistor connected in series to the power supply line; and

a switch transistor comprising a gate, a drain and a source, the gate being electrically connected to the selection line, the source being electrically connected to a node between the first resistor and the second resistor, and the drain being electrically connected to the capacitor to form a second node,

the method comprising;

dividing a potential supplied to the power supply line with the first resistor and the second resistor to obtain a wished potential;

applying the wished potential to the capacitor through the switch transistor when the switch transistor is turned on;

holding the wished potential at the second node when the switch transistor is turned off; and

applying the wished potential held at the second node through the capacitor.

25. A method of driving a semiconductor device according to claim 23,

wherein the semiconductor device comprises a potential controller transistor configured so that the first resistor and the second resistor are electrically connected to the power supply line through a source and a drain of the potential controller transistor, and

wherein the potential controller transistor is turned off when the switch transistor is turned off.