STORAGE CIRCUIT

• US 20120230078A1
• Filed: 03/05/2012
• Published: 09/13/2012
• Est. Priority Date: 03/11/2011
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Fujita, Masashi
• Granted Patent: US 8,760,903 B2
• Time in Patent Office: Days
• US Class Current: 365/65
• CPC Class Codes: G11C 14/00 Digital stores characterised by arrangements of cells having volatile and non-volatile storage properties for back-up when the power is down
• CPC Class Codes: G11C 14/0054 in which the volatile element is a SRAM cell
• CPC Class Codes: G11C 29/50004 of threshold voltage
• CPC Class Codes: G11C 5/06 Arrangements for interconnecting storage elements electrically, e.g. by wiring
• CPC Class Codes: G11C 5/14 Power supply arrangements , e.g. power down, chip selection or deselection, layout of wirings or power grids, or multiple supply levels

Abstract

A storage circuit includes a volatile storage portion in which storage of a data signal is controlled by a clock signal and an inverted clock signal, and a nonvolatile storage portion in which a data signal supplied to the volatile storage portion can be held even after supply of power supply voltage is stopped. A wiring which supplies a power supply voltage and is connected to a protective circuit provided for a wiring for supplying the clock signal is provided separately from a wiring which supplies a power supply voltage and which is connected to the storage circuit. The timing of stop and restart of supply of the power supply voltage supplied to the wiring which is connected to the protective circuit is different from that of stop and restart of supply of the power supply voltage supplied to the wiring which is connected to the storage circuit.

Claims

1. A semiconductor device comprising:

a first inverter circuit, an input terminal of the first inverter circuit being electrically connected to a first wiring supplied with a clock signal;

a volatile storage portion electrically connected to an output terminal of the first inverter circuit, the first wiring, and a second wiring supplied with a data signal;

a nonvolatile storage portion electrically connected to the volatile storage portion;

a first protective circuit electrically connected to the first wiring; and

a second protective circuit electrically connected to the second wiring,

wherein the volatile storage portion is electrically connected to a third wiring supplied with a first power supply voltage, and

wherein the first inverter circuit, the first protective circuit and the second protective circuit are electrically connected to a fourth wiring supplied with a second power supply voltage.

2. The semiconductor device according to claim 1, further comprising a third protective circuit and a fourth protective circuit,

wherein the nonvolatile storage portion comprises a first transistor, a second transistor, a third transistor and a fourth transistor,

wherein one of a source and a drain of the first transistor is electrically connected to the volatile storage portion,

wherein the other of the source and the drain of the first transistor is electrically connected to a gate of the second transistor,

wherein a gate of the third transistor is electrically connected to a gate of the fourth transistor,

wherein one of a source and a drain of the third transistor is electrically connected to the fourth wiring,

wherein one of a source and a drain of the fourth transistor is electrically connected to one of a source and a drain of the second transistor,

wherein the other of the source and the drain of the third transistor is electrically connected to the other of the source and the drain of the fourth transistor,

wherein a gate of the first transistor is electrically connected to a fifth wiring supplied with a first control signal,

wherein the gate of the third transistor and the gate of the fourth transistor are electrically connected to a sixth wiring supplied with a second control signal,

wherein the third protective circuit is electrically connected to the fifth wiring, and

wherein the fourth protective circuit is electrically connected to the sixth wiring.

3. The semiconductor device according to claim 2,

wherein the volatile storage portion comprises an analog switch, a second inverter circuit, a selector circuit and a clocked inverter circuit,

wherein the second wiring is electrically connected to an input terminal of the second inverter circuit through the analog switch,

wherein an output terminal of the second inverter circuit is electrically connected to a first input terminal of the selector circuit,

wherein an output terminal of the selector circuit is electrically connected to an input terminal of the clocked inverter circuit,

wherein an output terminal of the clocked inverter circuit is electrically connected to the input terminal of the second inverter circuit,

wherein a second input terminal of the selector circuit is electrically connected to the other of the source and the drain of the third transistor and the other of the source and the drain of the fourth transistor, and

wherein the one of the source and the drain of the first transistor is electrically connected to the output terminal of the selector circuit.

4. The semiconductor device according to claim 2,

wherein the nonvolatile storage portion further comprises a capacitor,

wherein a first electrode of the capacitor is electrically connected to the gate of the second transistor, and

wherein a second electrode of the capacitor is electrically connected to a seventh wiring supplied with a third power supply voltage.

5. The semiconductor device according to claim 2,

wherein the first transistor comprises a channel formation region comprising an oxide semiconductor.

6. The semiconductor device according to claim 1,

wherein each of the first protective circuit and the second protective circuit comprises a diode-connected transistor.

7. The semiconductor device according to claim 1,

wherein the nonvolatile storage portion comprises a ferroelectric random access memory, a magnetoresistive random access memory, or a phase change random access memory.

8. A semiconductor device comprising:

an inverter circuit configured to generate an inverted clock signal from a clock signal supplied through a first wiring;

a volatile storage portion configured to hold a data signal supplied through a second wiring by using the clock signal and the inverted clock signal while a first power supply voltage is supplied to the volatile storage portion through a third wiring;

a nonvolatile storage portion configured to hold the data signal that has been held in the volatile storage portion before supply of the first power supply voltage to the volatile storage portion stops, while the first power supply voltage is not supplied to the volatile storage portion through the third wiring;

a first protective circuit configured to discharge static electricity accumulated on the first wiring; and

a second protective circuit configured to discharge static electricity accumulated on the second wiring,

wherein a second power supply voltage is supplied to the inverter circuit, the first protective circuit and the second protective circuit through a fourth wiring.

9. The semiconductor device according to claim 8, wherein the nonvolatile storage portion is configured to store the data signal in accordance with a first control signal supplied through a fifth wiring and to send the stored data signal to the volatile storage portion in accordance with a second control signal supplied through a sixth wiring, the semiconductor device further comprising:

a third protective circuit configured to discharge static electricity accumulated on the fifth wiring; and

a fourth protective circuit configured to discharge static electricity accumulated on the sixth wiring.

10. The semiconductor device according to claim 8,

wherein each of the first protective circuit and the second protective circuit comprises a diode-connected transistor.

11. The semiconductor device according to claim 8,

wherein the nonvolatile storage portion comprises a ferroelectric random access memory, a magnetoresistive random access memory, or a phase change random access memory.

12. A semiconductor device comprising:

a volatile storage portion electrically connected to a first wiring supplied with a clock signal and a second wiring supplied with a data signal;

a nonvolatile storage portion electrically connected to the volatile storage portion;

a first protective circuit electrically connected to the first wiring; and

a second protective circuit electrically connected to the second wiring,

wherein the volatile storage portion is electrically connected to a third wiring supplied with a first power supply voltage, and

wherein the first protective circuit and the second protective circuit are electrically connected to a fourth wiring supplied with a second power supply voltage.

13. The semiconductor device according to claim 12, further comprising a third protective circuit and a fourth protective circuit,

wherein the nonvolatile storage portion comprises a first transistor, a second transistor, a third transistor and a fourth transistor,

wherein one of a source and a drain of the first transistor is electrically connected to the volatile storage portion,

wherein the other of the source and the drain of the first transistor is electrically connected to a gate of the second transistor,

wherein a gate of the third transistor is electrically connected to a gate of the fourth transistor,

wherein one of a source and a drain of the third transistor is electrically connected to the fourth wiring,

wherein one of a source and a drain of the fourth transistor is electrically connected to one of a source and a drain of the second transistor,

wherein the other of the source and the drain of the third transistor is electrically connected to the other of the source and the drain of the fourth transistor,

wherein a gate of the first transistor is electrically connected to a fifth wiring supplied with a first control signal,

wherein the gate of the third transistor and the gate of the fourth transistor are electrically connected to a sixth wiring supplied with a second control signal,

wherein the third protective circuit is electrically connected to the fifth wiring, and

wherein the fourth protective circuit is electrically connected to the sixth wiring.

14. The semiconductor device according to claim 13,

wherein the volatile storage portion comprises an analog switch, an inverter circuit, a selector circuit and a clocked inverter circuit,

wherein the second wiring is electrically connected to an input terminal of the inverter circuit through the analog switch,

wherein an output terminal of the inverter circuit is electrically connected to a first input terminal of the selector circuit,

wherein an output terminal of the selector circuit is electrically connected to an input terminal of the clocked inverter circuit,

wherein an output terminal of the clocked inverter circuit is electrically connected to the input terminal of the inverter circuit,

wherein a second input terminal of the selector circuit is electrically connected to the other of the source and the drain of the third transistor and the other of the source and the drain of the fourth transistor, and

wherein the one of the source and the drain of the first transistor is electrically connected to the output terminal of the selector circuit.

15. The semiconductor device according to claim 13,

wherein the nonvolatile storage portion further comprises a capacitor,

wherein a first electrode of the capacitor is electrically connected to the gate of the second transistor, and

wherein a second electrode of the capacitor is electrically connected to a seventh wiring supplied with a third power supply voltage.

16. The semiconductor device according to claim 13,

wherein the first transistor comprises a channel formation region comprising an oxide semiconductor.

17. The semiconductor device according to claim 12,

wherein each of the first protective circuit and the second protective circuit comprises a diode-connected transistor.

18. The semiconductor device according to claim 12,

wherein the nonvolatile storage portion comprises a ferroelectric random access memory, a magnetoresistive random access memory, or a phase change random access memory.