Amplifier circuit and display device

1. A differential amplifier circuit comprising:

first and second differential pairs;

one load circuit connected in common to said first and second differential pairs;

first and second current sources for supplying current to said first and second differential pairs, respectively;

said differential amplifier circuit performing an amplifying operation responsive to a common output signal of said first and second differential pairs, wherein said differential amplifier circuit further comprises circuits for modulating and controlling a current value of at least one of said first and second current sources, each of said first and second current sources includes two distinct current sources in parallel, one of the two distinct current sources is in series with a switch, operation of said switch modulates the current value, said first and second current sources are provides between a common source of each differential pair and a power supply.

2. A differential amplifier circuit comprising:

a load circuit connected to a first power supply;

first and second differential pairs connected in common to said load circuit;

first and second current sources for supplying currents to said first and second differential pairs, respectively;

an amplifying element for driving an output terminal upon receipt of an output connected in common to said first and second differential pairs;

a first switch connected between one input of said first differential pair and an input terminal;

a second switch connected between the one input of said first differential pair and said output terminal;

a third switch connected between one input of said second differential pair and said output terminal;

a capacitance element connected to the one input of said second differential pair; and

a fourth switch connected between said first differential pair and a second power supply, said fourth switch being connected in series with said first current source;

the other input of said first differential pair and the other input of said second differential pair being both connected to said input terminal.

3. The differential amplifier circuit according to claim 2 , wherein a fifth switch is connected between said second differential pair and a second power supply, said fifth switch being connected in series with said second current source.

4. The differential amplifier circuit according to claim 2 , wherein a data output period comprises a first period and a second period;

during the first period, said first and third switches are turned on, and said second switch is turned off;

during the second period, said first and third switches are turned off, and said second switch is turned on; and

said fourth switch is turned on after being turned off for a predetermined period after a start of the first period.

5. A differential amplifier circuit comprising:

a load circuit connected to a first power supply;

first and second differential pairs connected in common to said load circuit;

first and second current sources for supplying currents to said first and second differential pairs, respectively;

an amplifying element for driving an output terminal upon receipt of an output connected in common to said first and second differential pairs;

a first switch connected between one input of said first differential pair and an input terminal;

a second switch connected between the one input of said first differential pair and an output terminal;

a third switch connected between one input of said second differential pair and said output terminal;

a capacitance element connected to the one input of said second differential pair;

a fourth switch connected between said first differential pair and a second power supply, said fourth switch being connected in series with said first current source; and

a fifth switch connected between said second differential pair and said second power supply, said fifth switch being connected in series with said second current source;

the other input of said first differential pair being connected to said input terminal; and

the other input of said second differential pair being connected to a reference voltage input terminal.

6. The differential amplifier circuit according to claim 5 , wherein a data output period comprises a first period and a second period;

during the first period, said first and third switches are turned on, and said second switch is turned off;

during the second period, said first and third switches are turned off, and said second switch is turned on;

said fourth switch is turned on after being turned off for a predetermined period after a start of the first period; and

said fifth switch is turned off for a predetermined period after a start of the second period and turned on during periods other than the predetermined period after the start of the second period, in the data output period.

7. A differential amplifier circuit comprising:

a load circuit connected to a first power supply;

first and second differential pairs connected in common to said load circuit;

first and second current sources for supplying currents to said first and second differential pairs, respectively;

an amplifying element for driving an output terminal upon receipt of an output connected in common to said first and second differential pairs;

a first switch connected between one input of said first differential pair and an input terminal;

a second switch connected between the one input of said first differential pair and said output terminal;

a third switch connected between one input of said second differential pair and said output terminal; and

a capacitance element connected to the one input of said second differential pair;

the other input of said first differential pair and the other input of said second differential pair being both connected to said input terminal;

a series circuit comprising a third current source and a fourth switch being connected between said second differential pair and a second power supply, said series circuit being connected in parallel with said second current source.

8. The differential amplifier circuit according to claim 7 , wherein a data output period comprises a first period and a second period;

during the first period, said first and third switches are turned on, and said second switch is turned off;

during the second period, said first and third switches are turned off, and said second switch is turned on; and

said fourth switch is turned off after being turned on for a predetermined period after the start of the first period.

9. A differential amplifier circuit comprising:

a load circuit connected to a first power supply;

first and second differential pairs connected in common to said load circuit;

first and second current sources for supplying currents to said first and second differential pairs, respectively;

an amplifying element for driving an output terminal upon receipt of an output connected in common to said first and second differential pairs;

a first switch connected between one input of said first differential pair and an input terminal;

a second switch connected between the one input of said first differential pair and an output terminal;

a third switch connected between one input of said second differential pair and said output terminal; and

a capacitance element connected to the one input of said second differential pair;

the other input of said first differential pair being connected to said input terminal;

the other input of said second differential pair being connected to a reference voltage input terminal;

a series circuit comprising a third current source and a fourth switch being connected between said first differential pair and a second power supply, said series circuit being connected in parallel with said first current source;

a series circuit comprising a fourth current source and a fifth switch being connected between said second differential pair and said second power supply, said series circuit being connected in parallel with said second current source.

10. The differential amplifier circuit according to claim 9 , wherein a data output period comprises a first period and a second period;

during the first period, said first and third switches are turned on, and said second switch is turned off;

during the second period, said first and third switches are turned off, and said second switch is turned on;

said fifth switch is turned off after being turned on for a predetermined period after a start of the first period; and

said fourth switch is turned on for a predetermined period after a start of the second period and turned off during periods other than the predetermined period after the start of the second period, in the data output period.

11. A display device comprising an amplifier circuit for inputting a gray-scale voltage and driving a data line connected to display elements, wherein said display device comprises a differential amplifier circuit according to claim 1 as said amplifier circuit.

12. A display device comprising an amplifier circuit for inputting a gray-scale voltage and driving a data line connected to display elements, wherein said display device comprises a differential amplifier circuit according to claim 2 as said amplifier circuit.

13. A display device comprising an amplifier circuit for inputting a gray-scale voltage and driving a data line connected to display elements, wherein said display device comprises a differential amplifier circuit according to claim 5 as said amplifier circuit.

14. A display device comprising an amplifier circuit for inputting a gray-scale voltage and driving a data line connected to display elements, wherein said display device comprises a differential amplifier circuit according to claim 7 as said amplifier circuit.

15. A display device comprising an amplifier circuit for inputting a gray-scale voltage and driving a data line connected to display elements, wherein said display device comprises a differential amplifier circuit according to claim 9 as said amplifier circuit.

16. A differential amplifier circuit comprising:

a load circuit connected to a first power supply;

first and second differential pairs connected in common to said load circuit;

first and second current sources for supplying currents to said first and second differential pairs, respectively;

an amplifying element for driving an output terminal upon receipt of an output connected in common to said first and second differential pairs;

a first switch connected between one input of said first differential pair and an input terminal;

a second switch connected between the one input of said first differential pair and said output terminal;

a third switch connected between one input of said second differential pair and said output terminal; and

a capacitance element connected to the one input of said second differential pair, the other input of said first differential pair and the other input of said second differential pair being both connected to said input terminal, wherein

said differential amplifier circuit further comprises circuits for controlling activation/deactivation of at least one of said first and second current sources.

17. A differential amplifier circuit comprising:

a load circuit connected to a first power supply;

first and second differential pairs connected in common to said load circuit;

first and second current sources for supplying currents to said first and second differential pairs, respectively;

an amplifying element for driving an output terminal upon receipt of an output connected in common to said first and second differential pairs;

a first switch connected between one input of said first differential pair and an input terminal;

a second switch connected between the one input of said first differential pair and said output terminal;

a third switch connected between one input of said second differential pair and said output terminal; and

a capacitance element connected to the one input of said second differential pair, the other input of said first differential pair and the other input of said second differential pair being both connected to said input terminal, wherein

said differential amplifier circuit further comprises circuits for modulating and controlling a current value of at least one of said first and second current sources.

18. A differential amplifier circuit comprising:

a load circuit connected to a first power supply;

first and second differential pairs connected in common to said load circuit;

first and second current sources for supplying currents to said first and second differential pairs, respectively;

an amplifying element for driving an output terminal upon receipt of an output connected in common to said first and second differential pairs;

a first switch connected between one input of said first differential pair and an input terminal;

a second switch connected between the one input of said first differential pair and said output terminal;

a third switch connected between one input of said second differential pair and said output terminal;

a capacitance element connected to the one input of said second differential pair, the other input of said first differential pair and the other input of said second differential pair being both connected to said input terminal, wherein

said differential amplifier circuit further comprises circuits for controlling activation/deactivation of at least one of said first and second differential pairs.