US 7,405,622 B2 · Operational amplifier with less offset

Abstract

A differential amplifier includes an input stage circuit including a first differential pair and a second differential pair which are complementary to each other; a first current mirror circuit connected with the first differential pair and configured to function as an active load; a second current mirror circuit connected with the second differential pair and configured to function as an active load; an output stage circuit having a pair of output transistors connected in series between a higher power supply and a lower power supply; an operation point setting circuit configured to set an operation point of the output transistors; and a floating constant current source connected between an input terminal of the first current mirror circuit and an input terminal of the second current mirror circuit, and configured to supply a constant current. The first current mirror circuit and the second current mirror circuit supply superimpose an output of the input stage circuit on a current corresponding to the constant current by the floating constant current source to supply to the operation point setting circuit.

Claims20

Dependent claims

An operational amplifier comprising:

an input stage circuit comprising a first differential pair and a second differential pair which are complementary to each other;
a first current mirror circuit connected with said first differential pair and configured to function as an active load;
a second current mirror circuit connected with said second differential pair and configured to function as an active load;
an output stage circuit having a pair of output transistors connected in series between a higher power supply and a lower power supply;
an operation point setting circuit configured to set an operation point of said output transistors;
and
a floating constant current source connected to a first connection node between an input terminal of said first current mirror circuit and said first differential pair, and a second connection node between an input terminal of said second current mirror circuit and said second differential pair, and configured to supply a constant current,
wherein said first current mirror circuit and said second current mirror circuit superimpose an output of said input stage circuit on a current corresponding to the constant current by said floating constant current source to supply to said operation point setting circuit.

5 more elements

An operational amplifier comprising:

an N-channel differential transistor pair connected with input terminals;
a P-channel differential transistor pair connected with the input terminals;
a first current mirror circuit provided between a higher power supply line and said N-channel differential transistor pair to have input and output terminals connected with differential outputs of said N-channel differential transistor pair;
a second current mirror circuit provided between a lower power supply line and said P-channel differential transistor pair to have input and output terminals connected with differential outputs of said P-channel differential transistor pair;
a floating constant current source having one terminal connected with the input terminal of said first current mirror circuit and the other terminal connected with the input terminal of said second current mirror circuit;
a P-channel MOS transistor having a source connected with the output terminal of said first current mirror circuit, a gate connected with a first constant voltage source, and a drain connected with the output terminal of said second current mirror circuit;
an N-channel MOS transistor having a source connected with the output terminal of said second current mirror circuit, a gate connected with a second constant voltage source and a drain connected with the output terminal of said first current mirror circuit;
an output stage P-channel MOS transistor connected between an external output terminal and the higher power supply line and having a gate connected with the output terminal of said first current mirror circuit;
and
an output stage N-channel MOS transistor connected between the external output terminal and the lower power supply line and having a gate connected with the output terminal of said second current mirror circuit.

7 more elements

An operational amplifier comprising:

an input stage circuit comprising a first differential pair and a second differential pair which are complementary to each other;
a first current mirror circuit connected with said first differential pair and configured to function as an active load;
a second current mirror circuit connected with said second differential pair and configured to function as an active load;
an output stage circuit having a pair of output transistors connected in series between a higher power supply and a lower power supply;
an operation point setting circuit configured to set an operation point of said output transistors;
a floating constant current source connected between an input terminal of said first current mirror circuit and an input terminal of said second current mirror circuit, and configured to supply a constant current;
and
a plurality of constant voltage sources.

5 more elements

Dependencies are inferred from the claim text.

Operational amplifier with less offset

Life of this patent

Operational amplifier with less offset

Life of this patent

Abstract

Claims20