Magnetic Field Sensor and Electronic Circuit That Pass Amplifier Current Through a Magnetoresistance Element

A magnetic field sensor coupled to receive a power supply voltage, comprising:

• a substrate;
• and
• an electronic circuit disposed upon the substrate, the electronic circuit comprising:
• a first magnetoresistance element having first and second terminals;
• a first transistor having a control node, a first current passing node, and a second current passing node;
• and
• a first voltage generating source having first and second nodes between which a first fixed voltage is generated, wherein the first terminal of the first magnetoresistance element is coupled to the first current passing node of the first transistor, wherein the control node of the first transistor is coupled to receive the first fixed voltage, and the second node of the first voltage generating source is coupled to the second terminal of the first magnetoresistance element, wherein the electronic circuit is operable to generate a first current signal at the second current passing node of the first transistor related to a resistance value of the first magnetoresistance element, wherein the electronic circuit further comprises:
• a second magnetoresistance element having first and second terminals;
• a second transistor having a control node, a first current passing node, and a second current passing node;
• a second voltage generating source having first and second nodes between which a second fixed voltage is generated;
• and
• a load coupled to the second current passing node of the first transistor, wherein the second current passing node of the first transistor is coupled to the second current passing node of the second transistor, wherein the first terminal of the second magnetoresistance element is coupled to the first current passing node of the second transistor, wherein the control node of the second transistor is coupled to receive the second fixed voltage, and the second node of the second voltage generating source is coupled to the second terminal of the second magnetoresistance element, wherein the electronic circuit is operable to generate a second current signal at the second current passing node of the second transistor related to a resistance value of the second magnetoresistance element, wherein a current passing through the load is equal to a difference between the first current signal and the second current signal.

A magnetic field sensor coupled to receive a power supply voltage, comprising:

• a substrate;
• and
• an electronic circuit disposed upon the substrate, the electronic circuit comprising:
• a first magnetoresistance element having first and second terminals;
• a first transistor having a control node, and first current passing node, and a second current passing node;
• a first voltage generating source having first and second nodes between which a first fixed voltage is generated, wherein the first terminal of the first magnetoresistance element is coupled to the first current passing node of the first transistor, wherein the control node of the first transistor is coupled to receive the first fixed voltage, and the second node of the first voltage generating source is coupled to the second terminal of the first magnetoresistance element, wherein the electronic circuit is operable to generate a first current signal at the second current passing node of the first transistor related to a resistance value of the first magnetoresistance element, wherein the electronic circuit further comprises:
• a second magnetoresistance element having first and second terminals;
• a second transistor having a control node, a first current passing node, and a second current passing node;
• and
• a second voltage generating source having first and second nodes between which a second fixed voltage is generated;
• a load coupled to the second current passing node of the first transistor, wherein the second current passing node of the first transistor is coupled to the second current passing node of the second transistor, wherein the first terminal of the second magnetoresistance element is coupled to the first current passing node of the second transistor, wherein the control node of the second transistor is coupled to receive the second fixed voltage, and the second node of the second voltage generating source is coupled to the second terminal of the second magnetoresistance element, wherein the electronic circuit is operable to generate a second current signal at the second current passing node of the second transistor related to a resistance value of the second magnetoresistance element, wherein a current passing through the load is equal to a difference between the first current signal and the second current signal, wherein the electronic circuit further comprises:
• a third magnetoresistance element having first and second terminals;
• a third transistor having a control node, and first current passing node, and a second current passing node;
• and
• a third voltage generating source having first and second nodes between which a third fixed voltage is generated, wherein the first terminal of the third magnetoresistance element is coupled to the first current passing node of the third transistor, wherein the control node of the third transistor is coupled to receive the third fixed voltage, and the second node of the third voltage generating source is coupled to the second terminal of the third magnetoresistance element, wherein the electronic circuit is operable to generate a third current signal at the second current passing node of the third transistor related to a resistance value of the third magnetoresistance element, wherein the electronic circuit further comprises:
• a fourth magnetoresistance element having first and second terminals;
• a fourth transistor having a control node, a first current passing node, and a second current passing node;
• a fourth voltage generating source having first and second nodes between which a fourth fixed voltage is generated;
• and
• a second load coupled to the second current passing node of the third transistor, wherein the second current passing node of the third transistor is coupled to the second current passing node of the fourth transistor, wherein the first terminal of the fourth magnetoresistance element is coupled to the first current passing node of the fourth transistor, wherein the control node of the fourth transistor is coupled to receive the fourth fixed voltage, and the second node of the fourth voltage generating source is coupled to the second terminal of the fourth magnetoresistance element, wherein the electronic circuit is operable to generate a fourth current signal at the second current passing node of the fourth transistor related to a resistance value of the fourth magnetoresistance element, wherein a current passing through the second load is equal to a difference between the third current signal and the fourth current signal.