Current sensing of switching power regulators
AssigneeAnalog Devices Global
InventorSong Qin
Life of this patent
Estimating the term…
Abstract
Apparatus and methods for current sensing in switching regulators include a current sensing circuit to sense current of a power stage of a power converter. The power converter can include first and second transistors. The current sensing circuit comprises a transistor that is a scaled version of one of the transistors of the power converter. A circuit of the current sensing circuit matches a drain-to-source voltage of the transistor of the current sensing circuit to the corresponding transistor of the power converter. A current mirror generates a current that mirrors the current flowing through the transistor of the current sensing circuit. A first resistor converts the mirrored current to a current sensed signal.
Claims20
An apparatus for sensing a current of a power converter, the apparatus comprising:
- a power stage electrically coupled to a first supply, the power stage comprising a first transistor and a second transistor;
- a current sensing circuit configured to sense current of the power stage, the current sensing circuit comprising:
- a third transistor having a gate, a drain, and a source, wherein the gate of the third transistor is operatively coupled to a gate of the second transistor, wherein the third transistor is a scaled version of the second transistor;
- a first circuit configured to match a drain-to-source voltage of the third transistor with a drain-to-source voltage of the second transistor;
- a current mirror electrically coupled to a second supply and configured to provide a mirrored current mirroring current flowing through the third transistor, the mirrored current supplied by the second supply;
- and
- a first resistor configured to convert the mirrored current to a current sensed signal.
A method of sensing a current of a power converter, the method comprising:
- supplying the current of the power converter using a first supply;
- providing a gate of a sensing transistor with a voltage corresponding to a gate voltage of a power transistor of the power converter, wherein the sensing transistor is a scaled version in width relative to the power transistor;
- controlling a drain-to-source voltage of the sensing transistor to match a drain-to-source voltage of the power transistor, wherein a polarity of the drain-to-source voltage determines a direction of current flow through the sensing transistor;
- generating an output current based at least partly on current flowing through the sensing transistor by using a current mirror such that the output current is a scaled version of the current flowing through the sensing transistor;
- supplying the output current using a second supply;
- and
- converting the output current to a current sensed signal by using a first resistor.
An apparatus for sensing a current of a power converter, the apparatus comprising:
- means for supplying power to the power converter using a first supply;
- means for providing a gate of a sensing transistor a voltage corresponding to a gate voltage of a power transistor of the power converter, wherein the sensing transistor is a scaled version in width relative to the power transistor;
- means for controlling a drain-to-source voltage of the sensing transistor to match a drain-to-source voltage of the power transistor;
- means for controlling a current flow direction in the sensing transistor by controlling a polarity of the drain-to-source voltage of the sensing transistor to be same polarity or the reverse polarity as that of the drain-to-source voltage of the power transistor;
- means for generating an output current based at least partly on current flowing through the sensing transistor, wherein the output-current generating means includes a current mirror such that the output current is a scaled version of the current flowing through the sensing transistor and such that the output current is provided by a second supply;
- and
- means for converting the output current to a current sensed signal.
Dependencies are inferred from the claim text.