Current sensor, magnetic sensor and circuit

A magnetic sensor comprising:

• a magnetic detecting device that changes the electrical resistance in response to a change in a magnetic field to be measured;
• two coils that generate a canceling magnetic field to cancel said magnetic field to be measured and that are arranged in the vicinity of said magnetic detecting device;
• a shunt resistor, that is connected in series between said two coils, for detecting a current flowing through said coils;
• a first differential amplifier that amplifies the output signal of said magnetic detecting device and that supplies the current to induce said canceling magnetic field to said coils;
• and
• a second differential amplifier that amplifies the voltage across said shunt resistor and that outputs a measured voltage proportional to the current flowing through said conductor.

A circuit comprising:

• a magnetic detecting device that changes the electrical resistance in response to a change in a magnetic field to be measured;
• two coils that generate a canceling magnetic field to cancel said magnetic field to be measured and that are arranged in the vicinity of said magnetic detecting device;
• a shunt resistor, that is connected in series between said two coils, for detecting a current flowing through said coils;
• a first differential amplifier that amplifies the output signal of said magnetic detecting device and that supplies the current to induce said canceling magnetic field to said coils;
• and
• a second differential amplifier that amplifies the voltage across said shunt resistor and that outputs a measured voltage proportional to the current flowing through said conductor.