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US 9,071,205 B2Granted
Single input class-AB rail-to-rail output stage
AssigneeAnalog Devices, Inc.
InventorsDaniel Rey-Losada, Corey Petersen
Life of this patent
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Abstract
An amplifier with a single-input class-AB output stage comprises an input stage providing a signal to an output stage. The output stage comprises a current-splitting stage having a bias current and providing at least two intermediate output currents, and a drive stage receiving the two intermediate output currents and driving an output signal having a positive side and a negative side.
Claims20
A single-input class-AB output stage comprising:
- a current-splitting stage comprising:
- a signal current;
- a tail current, the signal current and tail current together forming a splitting-stage current;
- a first cascode three-node transistor wherein the first node receives a cascode biasing voltage, the second node is driven by the splitting-stage current, and the third node provides a first intermediate output current;
- and
- a second cascode three-node transistor wherein the first node is biased to the cascode biasing voltage, the second node is driven by the splitting-stage current, and the third node provides a second intermediate output current;
- whereby the splitting-stage current is split between the second nodes of the cascode transistors and whereby each cascode transistor provides at its third node a current substantially identical to the current provided at its second node;
- and
- a drive stage comprising a first intermediate input current receiving the first intermediate output current of the current-splitting stage and a second intermediate input current receiving the second intermediate output current of the current-splitting stage, the first intermediate input current driving a first output three-node transistor and the second intermediate input current driving a second output three-node transistor.
6 more elements
An amplifier comprising:
- an input stage operable to provide a signal current having a positive side and a negative side;
- and
- a class-AB output stage comprising:
- a current-splitting stage comprising:
- a signal current source operable to provide a signal current;
- a tail current source operable to provide a tail current, the signal current and tail current together operable to form a splitting-stage current;
- a first cascode three-node transistor wherein the first node is operable to receive a cascode biasing voltage, the second node is operable to be driven by the splitting-stage current, and the third node is operable to provide a first intermediate output current;
- and a second cascode three-node transistor wherein the first node is biased to the cascode biasing voltage, the second node is operable to be driven by the splitting-stage current, and the third node is operable to provide a second intermediate output current;
- whereby the splitting-stage current is operable to be split between the second nodes of the cascode transistors and whereby each cascode transistor is operable to provide at its third node a current substantially identical to the current provided at its second node;
- and
- a drive stage comprising a first intermediate input current operable to receive the first intermediate output current of the current-splitting stage and a second intermediate input current operable to receive the second intermediate output current of the current-splitting stage, the first intermediate input current operable to drive a first output three-node transistor and the second intermediate input current operable to drive a second output three-node transistor.
8 more elements
A system on a chip, comprising:
- a mixed-signal analog-digital network configured to provide an output current;
- and
- an amplifier, comprising:
- an input stage providing a signal current having a positive side and a negative side;
- and
- a class-AB output stage comprising:
- a current-splitting stage comprising:
- a signal current source operable to provide a signal current;
- a tail current source operable to provide a tail current, the signal current and tail current together operable to provide a splitting-stage current;
- a first cascode three-node transistor wherein the first node is operable to receive a cascode biasing voltage, the second node is operable to be driven by the splitting-stage current, and the third node is operable to provide a first intermediate output current;
- and
- a second cascode three-node transistor wherein the first node is configured to be biased to the cascode biasing voltage, the second node is operable to be driven by the splitting-stage current, and the third node is operable to provide a second intermediate output current;
- whereby the splitting-stage current is split between the second nodes of the cascode transistors and whereby each cascode transistor provides at its third node a current substantially identical to the current provided at its second node;
- and
- a drive stage comprising a first intermediate input current source operable to receive the first intermediate output current of the current-splitting stage and a second intermediate input current source operable to receive the second intermediate output current of the current-splitting stage, the first intermediate input current operable to drive a first output three-node transistor and the second intermediate input operable to drive a second output three-node transistor.
12 more elements
Dependencies are inferred from the claim text.