Current sensing circuit with integrated resistor and dual sense amplifiers

A system comprising:

• a coil configured to receive wireless power;
• an integrated circuit comprising:
• a rectifier configured to receive alternating current from the coil and generate a first voltage (Vrect);
• a current sense circuit comprising:
• a first resistor coupled between a first node and a second node;
• wherein the first resistor has a first resistance (Rs);
• wherein the first resistor is configured to carry a first current (Isns) across the first resistor when the first node has the first voltage (Vrect) and the second node has a second voltage (Vmid);
• a first amplifier including a first input coupled to the first node and a second input coupled to the second node;
• the first amplifier configured to output a third voltage (Vo);
• a second resistor and a third resistor;
• wherein the second resistor and the third resistor each have a second resistance (Rt);
• wherein the second resistor is coupled between the first node and a first input of the first amplifier;
• wherein the third resistor is coupled between the second node and a second input of the first amplifier;
• a plurality of switches for measuring an offset of the current sense circuit;
• and
• a second amplifier including a third input coupled to the first node and a fourth input coupled to the second node;
• the second amplifier configured to output a fourth voltage (Van);
• a voltage regulator configured to regulate the second voltage (Vmid);
• and
• a processor;
• wherein the processor is configured to receive one or more digital signals of the third voltage (Vo);
• wherein the processor is configured determine the current (Isns) based on the third voltage (Vo);
• and
• a battery charging system.