US 8,970,302 B2Granted

Operational amplifier with selective input

AssigneePower Integrations, Inc.

InventorFrank Joseph Schulz

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Abstract

An operational amplifier includes a selective differential stage including a first current mirror and a current distribution circuit. First and second legs of the first current mirror are responsive to current in first and second paths of the current distribution circuit, which distributes a tail current in response to a first signal received by a first input of the operational amplifier. Current in a first path of a selection circuit in the second path of the current distribution circuit is responsive to a second signal received by a second input of the operational amplifier. Current in the second path of the selection circuit is responsive to a third signal received by a third input of the operational amplifier. An output stage generates an output signal responsive to a difference between the first signal and one of the second and third signals.

Claims22

Dependent claims

An operational amplifier, comprising:

a selective differential stage including:
a first current mirror having first and second legs;
a current distribution circuit including first and second paths, wherein the first and second legs of the first current mirror are coupled to be responsive to current in the first and second paths of the current distribution circuit, wherein the first and second paths of the current distribution circuit are coupled to distribute a tail current in response to a first signal coupled to be received by a first input of the operational amplifier;
and
a selection circuit included in the second path of the current distribution circuit, wherein the selection circuit includes first and second paths, wherein current in the first path of the selection circuit is coupled to be responsive to a second signal coupled to be received by a second input of the operational amplifier, and wherein current in the second path of the selection circuit is coupled to be responsive to a third signal coupled to be received by a third input of the operational amplifier;
and
an output stage coupled to generate an output signal responsive to the selective differential stage, wherein the output signal is responsive to a difference between the first signal and one of the second and third signals.

4 more elements

A voltage follower circuit, comprising:

an operational amplifier having first, second and third inputs, and an output, wherein the output of the operational amplifier is coupled to the first input of the operational amplifier, wherein the second input of the operational amplifier is coupled to receive a limiting signal, wherein the third input of the operational amplifier is coupled to receive an input signal, wherein the operational amplifier includes:
a selective differential stage including:
a first current mirror having first and second legs;
a current distribution circuit including first and second paths, wherein the first and second legs of the first current mirror are coupled to be responsive to current in the first and second paths of the current distribution circuit, wherein the first and second paths of the current distribution circuit are coupled to distribute a tail current in response to the first input of the operational amplifier;
and
a selection circuit included in the second path of the current distribution circuit, wherein the selection circuit includes first and second paths, wherein current in the first path of the selection circuit is coupled to be responsive to the second input of the operational amplifier, and wherein current in the second path of the selection circuit is coupled to be responsive to the third input of the operational amplifier;
and
an output stage coupled to generate an output signal of the operational amplifier responsive to the selective differential stage, wherein the output signal is responsive to a difference between the first signal and a lesser of the second and third signals;
and
an output load coupled to the output of the operational amplifier.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/958,865Filed 5 Aug 2013
Published: US 2015/0035597 A15 Feb 2015
Granted: 3 Mar 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H03F 3/45273
Using MOSFET transistors as the active amplifying circuit: mirror types
H03F 1/0277
In transistor amplifiers: selecting one or more amplifiers from a plurality of amplifiers
H03F 3/45192
Long tailed pairs: folded cascode stages
H03F 2203/45124
Indexing scheme relating to differential amplifiers: the folded cascode stage of the folded cascode dif amp being a current mirror