US 5,424,681 AGranted

Wide range operational amplifier

AssigneeNEC Corporation

InventorMichio Yotsuyanagi

Life of this patent

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Abstract

An operational amplifier includes a transistor differential pair having a common source terminal which is coupled to a first power supply terminal through a first current source circuit. A first transistor is provided which has a gate coupled to a first input terminal of the transistor differential pair, a source coupled to a first output of the transistor differential pair, and a drain coupled to a first output terminal. A second current source circuit is coupled between the first power supply terminal and the drain of the first transistor. A second transistor has a gate coupled to a second input terminal of the transistor differential pair, a source coupled to a second output of the transistor differential pair, and a drain coupled to a second output terminal. A third current source circuit is coupled between the first power supply terminal and the drain of the second transistor. A fourth current source circuit is coupled between the source of the first transistor and the second power supply terminal. A fifth current source circuit is coupled between the source of the second transistor and the second power supply terminal. The input signals of the transistor pair are applied to the gates of the source-input transistors connected to the transistor differential pair.

Claims7

Dependent claims

An operational amplifier comprising:

a first power supply terminal and a second power supply terminal;
a first input terminal and a second input terminal;
a first output terminal and a second output terminal;
a first current source circuit;
a second current source circuit;
a third current source circuit;
said first, second, and third current source circuits being connected to the first power supply terminal;
a transistor differential pair connected to the first and second input terminals and coupled to the first power supply terminal through the first current source circuit;
a first transistor having a control terminal which is coupled to the first input terminal, one terminal of a current path which is coupled to a first output of the transistor differential pair, and another terminal of the current path which is coupled to the first output terminal and the first power source terminal through the second current source circuit;
a second transistor having a control terminal which is coupled to the second input terminal, one terminal of a current path which is coupled to a second output of the transistor differential pair, and another terminal of the current path which is coupled to the second output terminal and the first power source terminal through the third current source circuit;
a fourth current source circuit coupled between the one terminal of the current path of the first transistor and the second power supply terminal;
and
a fifth current source circuit coupled between the one terminal of the current path of the second transistor and the second power supply terminal.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/272,262Filed 8 Jul 1994
Priority: JP 5-17303113 Jul 1993
Granted: 13 Jun 1995
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

H03F 3/4508
Characterised by the way of implementation of the active amplifying circuit in the differential amplifier: using bipolar transistors as the active…
H03F 3/45179
Characterised by the way of implementation of the active amplifying circuit in the differential amplifier: using MOSFET transistors as the active…
H03F 3/45192
Long tailed pairs: folded cascode stages
H03F 2203/45028
Indexing scheme relating to differential amplifiers: the differential amplifier amplifying transistors are folded cascode coupled transistors