Voltage regulator and method of controlling voltage regulator

1. A voltage regulator which includes a differential amplifier circuit containing a first input transistor and a second input transistor and is configured to control a gate-source voltage in each of the first input transistor and the second input transistor respectively being a PMOS transistor comprising:

a current source containing a current source output port, being configured to drive the differential amplifier circuit;

the first input transistor containing a source connected to the current source output port via a tail connection point and a gate to which a reference voltage is supplied;

the second input transistor containing a source connected to the tail connection point and a gate connected to the output terminal; and

a voltage controller including at least one of a first voltage control circuit which is interposed between the tail connection point and the gate of the first input transistor and is configured to control a voltage at the tail connection point based on a voltage at the gate of the first input transistor, a second voltage control circuit which contains a first port connected to the gate of the first input transistor, a second port connected to a grounding point, and a third port connected to the gate of the second input transistor and is configured to control the voltage at the gate of the first input transistor based on a voltage at the gate of the second input transistor, a third voltage control circuit which is interposed between the tail connection point and the gate of the second input transistor and is configured to control the voltage at the tail connection point based on the voltage at the gate of the second input transistor, and a fourth voltage control circuit which contains a first port connected to the gate of the second input transistor, a second port connected to the grounding point, and a third port connected to the gate of the first input transistor and is configured to control the voltage at the gate of the second input transistor based on the voltage at the gate of the first input transistor.

2. The voltage regulator according to claim 1 , wherein the voltage controller includes the first voltage control circuit controlling the voltage at the tail connection point if the short-circuit occurs between the output terminal and the ground and the second voltage control circuit controlling the voltage at the tail connection point and the voltage at the gate of the first input transistor if the short-circuit occurs between the output terminal and the ground, and controls to provide a predetermined voltage difference between the gate-source voltage of the first input transistor and the gate-source voltage of the second input transistor.

3. The voltage regulator according to claim 2 ,

wherein the first voltage control circuit is configured to limit the voltage at the tail connection point, and

wherein the second voltage control circuit is configured to limit the voltage at the gate of the first input transistor.

4. The voltage regulator according to claim 2 , further comprising:

a first resistor interposed between the tail connection point and the source of the first input transistor; and

a fifth voltage control circuit interposed between the grounding point and a connection point between the first resistor and the source of the first input transistor,

wherein the fifth voltage control circuit is configured to control the gate-source voltage of the first input transistor to a voltage lower than a threshold voltage of the first input transistor based on the voltage at the gate of the first input transistor.

5. The voltage regulator according to claim 3 , further comprising:

a first resistor interposed between the tail connection point and the source of the first input transistor; and

a fifth voltage control circuit interposed between the grounding point and a connection point between the first resistor and the source of the first input transistor;

wherein the fifth voltage control circuit is configured to control the gate-source voltage of the first input transistor to a voltage lower than a threshold voltage of the first input transistor based on the voltage at the gate of the first input transistor.

6. The voltage regulator according to claim 1 , wherein the voltage controller includes the third voltage control circuit controlling the voltage at the tail connection point if the short-circuit occurs between the output terminal and the ground and the fourth voltage control circuit controlling the voltage at the tail connection point and the voltage at the gate of the second input transistor if the short-circuit occurs between the output terminal and the ground, and controls to provide a predetermined voltage difference between the gate-source voltage of the first input transistor and the gate-source voltage of the second input transistor.

7. The voltage regulator according to claim 2 , wherein the voltage controller includes the third voltage control circuit controlling the voltage at the tail connection point if the short-circuit occurs between the output terminal and the ground and the fourth voltage control circuit controlling the voltage at the tail connection point and the voltage at the gate of the second input transistor if the short-circuit occurs between the output terminal and the ground, and controls to provide a predetermined voltage difference between the gate-source voltage of the first input transistor and the gate-source voltage of the second input transistor.

8. The voltage regulator according to claim 3 , wherein the voltage controller includes the third voltage control circuit controlling the voltage at the tail connection point if the short-circuit occurs between the output terminal and the ground and the fourth voltage control circuit controlling the voltage at the tail connection point and the voltage at the gate of the second input transistor if the short-circuit occurs between the output terminal and the ground, and controls to provide a predetermined voltage difference between the gate-source voltage of the first input transistor and the gate-source voltage of the second input transistor.

9. The voltage regulator according to claim 4 , wherein the voltage controller includes the third voltage control circuit controlling the voltage at the tail connection point if the short-circuit occurs between the output terminal and the ground and the fourth voltage control circuit controlling the voltage at the tail connection point and the voltage at the gate of the second input transistor if the short-circuit occurs between the output terminal and the ground, and controls to provide a predetermined voltage difference between the gate-source voltage of the first input transistor and the gate-source voltage of the second input transistor.

10. The voltage regulator according to claim 5 , wherein the voltage controller includes the third voltage control circuit controlling the voltage at the tail connection point if the short-circuit occurs between the output terminal and the ground and the fourth voltage control circuit controlling the voltage at the tail connection point and the voltage at the gate of the second input transistor if the short-circuit occurs between the output terminal and the ground, and controls to provide a predetermined voltage difference between the gate-source voltage of the first input transistor and the gate-source voltage of the second input transistor.

11. The voltage regulator according to claim 6 ,

wherein the third voltage control circuit is configured to limit the voltage at the tail connection point, and

wherein the fourth voltage control circuit is configured to limit the voltage at the gate of the second input transistor.

12. The voltage regulator according to claim 7 ,

wherein the third voltage control circuit is configured to limit the voltage at the tail connection point, and

wherein the fourth voltage control circuit is configured to limit the voltage at the gate of the second input transistor.

13. The voltage regulator according to claim 6 , further comprising,:

a second resistor, interposed between the tail connection point and the source of the second input transistor; and

a sixth voltage control circuit interposed between the grounding point and a connection point between the second resistor and the source of the second input transistor,

wherein the sixth voltage control circuit is configured to control the gate-source voltage of the second input transistor to a voltage lower than a threshold voltage of the second input transistor based on the voltage at the gate of the second input transistor.

14. The voltage regulator according to claim 7 , further comprising:

a second resistor interposed between the tail connection point and the source of the second input transistor; and

a sixth voltage control circuit interposed between the grounding point and a connection point between the second resistor and the source of the second input transistor,

wherein the sixth voltage control circuit is configured to control the gate-source voltage of the second input transistor to a voltage lower than a threshold voltage of the second input transistor based on the voltage at the gate of the second input transistor.

15. The voltage regulator according to claim 8 , further comprising:

a second resistor interposed between the tail connection point and the source of the second input transistor; and

a sixth voltage control circuit interposed between the grounding point and a connection point, between the second resistor and the source of the second input transistor,

wherein the sixth voltage control circuit is configured to control the gate-source voltage of the second input transistor to a voltage lower than a threshold voltage of the second transistor based on the voltage at the gate of the second input transistor.

16. The voltage regulator according to claim 9 , further comprising:

a second resistor interposed between the tail connection point and the source of the second transistor; and

a sixth voltage control circuit interposed between the grounding point and a connection point between the second resistor and the source of the second input transistor,

wherein the sixth voltage control circuit configured to control the gate-source voltage of the second input transistor to a voltage lower than a threshold voltage of the second input transistor based on the voltage at the gate of the second input transistor.

17. The voltage regulator according to claim 10 , further comprising:

a second resistor interposed between the tail connection point and the source of the second input transistor; and

a sixth voltage control circuit interposed between the grounding point and a connection point between the second resistor and the source of the second input transistor,

wherein the sixth voltage control circuit is configured to control the gate-source voltage of the second input transistor to a voltage lower than a threshold voltage of the second input transistor based on the voltage at the gate of the second input transistor.

18. The voltage regulator according to claim 11 , further comprising:

a second resistor interposed between the tail connection point and the source of the second input transistor; and

a sixth voltage control circuit interposed between the grounding point and a connection point between the second resistor and the source of the second input transistor,

wherein the sixth voltage control circuit is configured to control the gate-source voltage of the second input transistor to a voltage lower than a threshold voltage of the second input transistor based on the voltage at the gate of the second input transistor.

19. The voltage regulator according to claim 12 , further comprising:

a second resistor interposed between the tail connection point and the source of the second input transistor; and

a sixth voltage control circuit interposed between the grounding point and a connection point between the second resistor and the source of the second input transistor,

wherein the sixth voltage control circuit is configured to control the gate-source voltage of the second input transistor to a voltage lower than a threshold voltage of the second input transistor based on the voltage at the gate of the second input transistor.

20. A method of controlling a voltage regulator which includes a current source configured to drive a differential amplifier circuit, a first input transistor, and a second input transistor, the first input transistor being a PMOS transistor containing a source connected to a current source output terminal of the current source via a tail connection point and containing a gate to which a reference voltage is input, the second input transistor being a PMOS transistor containing a source connected to the tail connection point and containing a gate connected to an output terminal, the voltage regulator being configured to control, if a short circuit occurs between the output terminal configured to output a predetermined output voltage and a ground, a gate-source voltage of each of the first input transistor and the second input transistor in the differential amplifier circuit configured to control the predetermined output voltage the method comprising:

preparing a voltage controller including at least one of a first voltage control circuit which is interposed between the tail connection point and the gate of the first input transistor and is configured to control a voltage at the tail connection point based on a voltage at the gate of the first input transistor, a second voltage control circuit which contains a first port connected to the gate of the first input transistor, a second port connected to a grounding point, and a third port connected to the gate of the second input transistor and is configured to control the voltage at the gate of the first input transistor based on a voltage at the gate of the second input transistor, a third voltage control circuit which is interposed between the tail connection point and the gate of the second input transistor and is configured to control the voltage at the tail connection point based on the voltage at the gate of the second input transistor, and a fourth voltage control circuit which contains a first port connected to the gate of the second input transistor, a second port connected to the grounding point, and a third port connected to the gate of the first input transistor and is configured to control the voltage at the gate of the second input transistor based on the voltage at the gate of the first input transistor; and

performing a voltage control by the voltage controller, the voltage control including at least one of controlling a voltage at the tail connection point based on a voltage at the gate of the first input transistor, controlling the voltage at the gate of the first input transistor based on a voltage at the gate of the second input transistor, controlling the voltage at the tail connection point based on the voltage at the gate of the second input transistor, and controlling the voltage at the gate of the second input transistor based on a voltage at the gate of the second input transistor.