APPARATUS AND METHODS FOR BIDIRECTIONAL CURRENT SENSING IN A SWITCHING REGULATOR

摘要

Apparatus and methods for current sensing in switching regulators are provided. In certain implementations, a switching regulator includes a switch transistor, a replica transistor, a current source, a sense resistor, and a current sensing circuit. The drain and gate of the switch transistor can be electrically connected to the drain and gate of the replica transistor, respectively. Additionally, the current sensing circuit can control the voltage of the source of the replica transistor based on the polarity of a current through the switch transistor to generate an output current that changes in response to the switch transistor's current. The sense resistor can receive an offset current from the first current source and the output current from the current sensing circuit such that the voltage across the sense resistor changes in relation to the current through the switch transistor.

主权项

1. An apparatus comprising:
a first switch transistor including a drain, a source, and a gate, wherein the source is electrically connected to a first supply voltage, and wherein the gate is electrically connected to a first control signal; a replica transistor including a drain, a source, and a gate, wherein the drain of the replica transistor is electrically connected to the drain of the first switch transistor, wherein the gate of the replica transistor is electrically connected to the first control signal, and wherein the replica transistor is a replica of the first switch transistor; a current sensing circuit electrically connected to the drain of the first switch transistor and to the source of the replica transistor, wherein the current sensing circuit is configured to generate an output current that varies in response to a sense current from a source of the replica transistor, wherein the sense current is a replica of a switch current through the first switch transistor by controlling a voltage of the source of the replica transistor, wherein the current sensing circuit is further configured to control the voltage of the source of the replica transistor to a first voltage level when the switch current has a first polarity, and wherein the current sensing circuit is further configured to control the voltage of the source of the replica transistor to a second voltage level different than the first voltage level when the switch current has a second polarity opposite the first polarity; and a sense resistor configured to receive the output current from the current sensing circuit, wherein a voltage across the sense resistor is configured to change in relation to the switch current.