Differential amplifier circuit using quadritail circuit

A differential amplifier circuit comprising:

• a quadritail circuit and a differential circuit;
• said quadritail circuit including a first transistor pair of first and second MOS transistors, a second transistor pair of third and fourth MOS transistors, and a first constant current source for driving said first and second transistor pairs;
• drains of said first and second transistors being connected in common, drains of said third and fourth transistors being connected in common, and sources of said first to fourth transistors being connected in common to said first constant current source;
• and
• said differential circuit being composed of fifth and sixth MOS transistors and being driven by a current equal in value to sum of current of said first constant source and an output current of said quadritail circuit;
• wherein an input voltage is differentially applied between gates of said first and second transistors and between gates of said fifth and sixth transistors, respectively;
• a DC voltage is applied to common-connected gates of said third and fourth transistors of said second transistor pair;
• and
• an output current of the differential amplifier circuit being derived from an output end of said differential circuit.

A differential amplifier circuit comprising:

• a quadritail circuit including a first transistor pair of first and second MOS transistors, a second transistor pair of third and fourth MOS, transistors, and a first constant current source for driving said first and second transistor pairs;
• drains of said first and second transistors being connected in common, drains of said third and fourth transistors being connected in common, and sources of said first to fourth transistors being connected in common to said first constant current source;
• a second constant current source connected to said common-connected drains of said first and second transistors;
• a differential circuit composed of fifth an sixth MOS transistors;
• a third constant current source for driving said differential pair, said third constant current source being connected to said common-connected drains of said first and second transistors;
• and
• a current level shifter for shifting a current level between said common-connected drains of said first and second transistors and common-connected sources of said fifth and sixth transistors;
• wherein an input voltage is differentially applied between gates of said first and second transistors and between gates of said fifth and sixth transistors, respectively;
• a DC voltage is applied to common-connected gates of said third and fourth transistors of said second transistor pair;
• and
• an output current of the differential amplifier circuit being derived from an output end of said differential circuit.

A differential amplifier circuit comprising:

• a quadritail circuit and a differential circuit;
• said quadritail circuit including a first transistor pair of first and second MOS transistors, a second transistor pair of third and fourth MOS transistors, and a first constant current source for driving said first and second transistor pairs;
• drains of said first and second transistors being connected in common, drains of said third and fourth transistors being connected in common, and sources of said first to fourth transistors being connected in common to said constant current source;
• and
• said differential circuit being composed of fifth and sixth MOS transistors and being driven by a current equal in value to an output current of said quadritail circuit;
• wherein an input voltage is differentially applied between gates of said fifth and sixth transistors and a voltage obtained by changing a voltage level of said input voltage is differentially applied between gates of the first and second transistors;
• a DC voltage generated from said level-changed voltage is applied to common-connected gates of said third and fourth transistors of said second transistor pair;
• and
• an output current being derived from an output end of said differential circuit.

A differential amplifier circuit comprising:

• a quadritail circuit and a differential circuit;
• said quadritail circuit including a first transistor pair of first and second MOS transistors, a second transistor pair of third and fourth MOS transistors, and a first constant current source for driving said first and second transistor pairs;
• drains of said first and second transistors being connected in common, drains of said third and fourth transistors being connected in common, and sources of said first to fourth transistors being connected in common to said constant current source;
• and
• said differential circuit being composed of firth and sixth MOS transistors and being driven by a current equal in value to an output current of said quadritail circuit;
• wherein an input voltage is differentially applied between gates of said first and second transistors and a voltage obtained by changing a voltage level of said input voltage is differentially applied between gates of the fifth and sixth transistors;
• a DC voltage generated from said input voltage is applied to common-connected gates of said third and fourth transistors of said second transistor pair;
• and
• an output current being derived from an output end of said differential circuit.