CURRENT SENSING OF SWITCHING POWER REGULATORS
First Claim
1. An apparatus comprising:
- a current sensing circuit configured to sense current of a power stage of a power converter comprising a first transistor and a second transistor, 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 configured to mirror current flowing through the third transistor; and
a first resistor configured to convert the mirrored current to a current sensed signal.
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Abstract
Apparatus and methods for current sensing in switching regulators are disclosed. In certain implementations, a current sensing circuit senses 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.
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Citations
20 Claims
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1. An apparatus comprising:
a current sensing circuit configured to sense current of a power stage of a power converter comprising a first transistor and a second transistor, 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 configured to mirror current flowing through the third transistor; and a first resistor configured to convert the mirrored current to a current sensed signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of sensing a current of a power converter, the method comprising:
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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 of the power transistor; controlling a drain-to-source voltage of the sensing transistor to match a drain-to-source voltage of the power 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; and converting the output current to a current sensed signal by using a first resistor. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. An apparatus for sensing a current of a power converter, the apparatus comprising:
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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 of 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 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 means for converting the output current to a current sensed signal.
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Specification