DC/DC converter and semiconductor device using DC/DC converter

• US 20080143425A1
• Filed: 12/11/2007
• Published: 06/19/2008
• Est. Priority Date: 12/13/2006
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Ito, Masafumi
• Granted Patent: US 7,974,111 B2
• Time in Patent Office: Days
• US Class Current: 327/536
• CPC Class Codes: H02M 3/073 Charge pumps of the Schenkel-type

Abstract

It is an object to provide a DC/DC converter that can stabilize power supply potential in use. It is another object to provide a semiconductor device in which circuit operation is stabilized. In addition to a power supply that supplies potential to be reference potential of boosting in a DC/DC converter, a power supply for charging a capacitor in the DC/DC converter is provided. Accordingly, loads to the power supply that supplies the reference potential of boosting can be reduced. Further, as power for charging the capacitor in the DC/DC converter, power supplied from not an antenna but a secondary battery is used. More specifically, a secondary battery is used as a power supply that supplies power to a buffer circuit or an inverter circuit. Thus, power supplied from the antenna can be stabilized. In other words, operation of a logic circuit and an analog circuit can be stabilized.

Claims

1. A semiconductor device comprising:

a DC/DC converter including;

n number of diodes connected in series between an input terminal and an output terminal of the DC/DC converter (n;

an integer, 3≦

n),

(n−

1) number of capacitors each including a first electrode, a second electrode, wherein the first electrode of one of the (n−

1) number of capacitors is connected to an output terminal of one of n number of diodes,

a circuit to supply a first potential is connected to an input terminal of the DC/DC converter;

a potential supply circuit to supply a second potential or a third potential selectively is connected to the second electrodes of the (n−

1) number of capacitors; and

wherein the potential supply circuit is a circuit by which the third potential is supplied to the second electrode of a (2k−

1)-th capacitor when the second potential is supplied to the second electrode of a 2k-th capacitor (k;

an integer, 2k≦

n−

1 and 2k−

1≦

n−

1), and by which the second potential is supplied to the second electrode of the (2k−

1)-th capacitor when the third potential is supplied to the second electrode of the 2k-th capacitor.

3. A semiconductor device according to claim 1 or 2,

wherein the third potential is a ground potential.

4. A semiconductor device according to claim 1 or 2,

wherein the potential supply circuit is provided with a circuit to switch destinations of the second potential and the third potential alternatively.

5. A semiconductor device according to claim 1 or 2,

wherein the potential supply circuit is provided with a buffer circuit or an inverter circuit.

6. A semiconductor device according to claim 1 or 2,

wherein a secondary battery that is charged by receiving power supplied wirelessly is used as a power supply to supply the second potential.

7. A semiconductor device according to claim 1 or 2,

wherein a secondary battery that is charged by receiving power supplied wirelessly is used as a power supply to supply the first potential.

2. A semiconductor device comprising:

a DC/DC converter including;

n number of diodes connected in series between an input terminal and an output terminal of the DC/DC converter (n;

an integer, 3≦

n); and

n number of capacitors each including a first electrode, a second electrode, wherein the first electrode of one of the n number of capacitors is connected to an output terminal of one of n number of diodes,

a circuit to supply a first potential is connected to an input terminal of the DC/DC converter;

a potential supply circuit to supply a second potential or a third potential selectively is connected to the second electrodes of first to (n−

1)-th capacitors,

wherein a circuit to supply the third potential is connected to the second electrode of a n-th capacitor; and

wherein the potential supply circuit is a circuit by which the third potential is supplied to the second electrode of a (2k−

1)-th capacitor when the second potential is supplied to the second electrode of a 2k-th capacitor (k;

an integer, 2k≦

n−

1 and 2k−

1≦

n−

1), and by which the second potential is supplied to the second electrode of the (2k−

1)-th capacitor when the third potential is supplied to the second electrode of the 2k-th capacitor.

8. A semiconductor device comprising:

a DC/DC converter including;

n number of diodes connected in series between an input terminal and an output terminal of the DC/DC converter (n;

an integer, 3≦

n); and

n number of capacitors each including a first electrode, a second electrode, wherein the first electrode of one of the n number of capacitors is connected to an output terminal of one of n number of diodes,

a first potential is supplied to an input terminal of the DC/DC converter from an antenna;

a potential supply circuit to supply a second potential from a secondary battery or a third potential selectively is connected to the other terminals of the (n−

1) number of capacitors;

wherein the third potential is supplied to the second electrode of an n-th capacitor, and

wherein the potential supply circuit is a circuit by which the third potential is supplied to the second electrode of a (2k−

1)-th capacitor when the second potential is supplied to the other terminal of a 2k-th capacitor (k;

an integer, 2k≦

n−

1 and 2k−

1≦

n−

1), and by which the second potential is supplied to the second electrode of the (2k−

1)-th capacitor when the third potential is supplied to the second electrode of the 2k-th capacitor.

9. A semiconductor device according to claim 8,

wherein the third potential is a ground potential.

10. A semiconductor device according to claim 8,

wherein the potential supply circuit is provided with a circuit to switch destinations of the second potential and the third potential alternatively.

11. A semiconductor device according to claim 8,

wherein the potential supply circuit is provided with a buffer circuit or an inverter circuit.

12. A semiconductor device according to claim 8,

wherein the secondary battery is a secondary battery that is charged by receiving power supplied wirelessly.

13. A semiconductor device according to claim 8,

wherein a potential from the secondary battery that is charged through a charge circuit by receiving power supplied wirelessly is used instead of the first potential from the antenna.

14. A semiconductor device comprising:

a DC/DC converter including;

n number of diodes connected in series between an input terminal and an output terminal of the DC/DC converter (n;

an integer, 3≦

n); and

the n number of capacitors each including a first electrode, a second electrode, wherein the first electrode of one of the n number of capacitors is connected to an output terminal of one of n number of diodes,

a circuit to supply a first potential from a first antenna is connected to an input terminal of the DC/DC converter;

a potential supply circuit to supply a second potential from a secondary battery that is charged by receiving power supplied from a second antenna or a third potential selectively is connected to the other terminals of first to (n−

1)-th capacitors;

wherein the third potential is supplied to the second electrode of an n-th capacitor; and

wherein the potential supply circuit is a circuit by which the third potential is supplied to the second electrode of a (2k−

1)-th capacitor when the second potential is supplied to the second electrode of a 2k-th capacitor (k;

an integer, 2k≦

n−

1 and 2k−

1≦

n−

1), and by which the second potential is supplied to the second electrode of the (2k−

1)-th capacitor when the third potential is supplied to the second electrode of the 2k-th capacitor.

15. A semiconductor device according to claim 14,

wherein the third potential is a ground potential.

16. A semiconductor device according to claim 14,

wherein the potential supply circuit is provided with a circuit to switch destinations of the second potential and the third potential alternatively.

17. A semiconductor device according to any one of claims 14,

wherein the potential supply circuit is provided with a buffer circuit or an inverter circuit.