A liquid crystal drive circuit for AC-driving a liquid crystal panel, the liquid crystal drive circuit including a switched capacitor type D/A converter having a sample period and a hold period, the liquid crystal drive circuit comprising:
- a differential operational amplifier;
- a first reference voltage connected to one input terminal of said differential operational amplifier;
- a first capacitor group connected to the other input terminal of said differential operational amplifier for dividing second and third reference voltages;
- a second capacitor group connected between an output terminal and the other input terminal of said differential operational amplifier;
- and
- switch means for changing a connection condition of said first capacitor group and said second capacitor group to said differential operational amplifier, said switch means being on-off controlled at every predetermined period for changing said connection condition, a plurality of liquid crystal drive circuits provided to realize a multi-output, and
- wherein said differential operational amplifier has a non-inverted input terminal connected to a first reference voltage input terminal, wherein said first capacitor group is constituted of a plurality of unitary capacitors as a basic element, which are connected to an inverted input terminal of said differential operational amplifier, said second capacitor group is constituted of a plurality of unitary capacitors as a basic element, which are connected to said inverted input terminal of said differential operational amplifier, and wherein said switch means comprises a “1A”th switch group having switches each having one end connected to a corresponding capacitor in said first capacitor group and the other end connected to a second reference voltage input terminal, a “2A”th switch group having switches each having one end connected to a corresponding capacitor in said first capacitor group, a “3A”th switch having one end connected to the other end of said “2A”th switch group and the other end connected to said inverted input terminal of said differential operational amplifier, a “4A”th switch having one end connected to the other end of said “2A” the switch group and the one end of said “3A”th switch and the other end connected to said output terminal of said differential operational amplifier, a “5A”th switch having one end connected to the other end of said “2A”th switch group, the one end of said “3A”th switch and the one end of said “4A”th switch and the other end connected to said first reference voltage input terminal and said non-inverted input terminal of said differential operational amplifier, and a “BA”th switch having one end connected to the other end of said “2A”th switch group and the respective one ends of said “3A”th to “5A”th switch and the other end connected to said third reference voltage input terminal, a “1B”th switch group having switches each having one end connected to a corresponding capacitor in said second capacitor group and the other end connected to said second reference voltage input terminal, a “2B”th switch group having switches each having one end connected to a corresponding capacitor in said second capacitor group, a “3B”th switch having one end connected to the other end of said “2B”th switch group and the other end connected to said inverted input terminal of said differential operational amplifier, a “4B”th switch having one end connected to the other end of said “2B”th switch group and said one end of said “3B”the switch and the other end connected to said output terminal of said differential operational amplifier, a“5B”th switch having one end connected to the other end of said “2B”th switch group, said one end of said “3B”th switch and said one end of said “4B”th switch and the other end connected to said first reference voltage input terminal and said non-inverted input terminal of said differential operational amplifier, and a “6B”th switch having one end connected to the other end of said “2B”th switch group and said respective one ends of said “3B”th to “5B”th switch and the other end connected to said third reference voltage input terminal.