Method and apparatus for measurement of electrical resistance

An electronic circuit to determine a resistance value of a first resistive element, the circuit comprising:

• a first current source coupled in series with the first resistive element, the first current source configured to force a first predetermined value of current through the first resistive element;
• a second resistive element coupled in series with the first resistive element and forming a node;
• a second current source coupled to the first current source such that the first resistive element is coupled therebetween, the second current source further coupled in series with the second resistive element at the node, the second current source configured to force a second predetermined value of current into the node;
• and
• a transconducting device coupled to both the first current source and the first an second resistive elements, the transconducting device configured to sense a first voltage across the first an second resistive elements coupled in series with one another, the transconducting device further configured to transform the first voltage into an output current of the transconducting device, the output current not being dependent upon any other terminal voltages of the transconducting device.

An electronic circuit to determine a resistance value of a resistive element, the circuit comprising:

• a current source coupled to the resistive element, the current source configured to force a predetermined value of current through the resistive element;
• a first transconducting device coupled to the resistive element, the first transconducting device configured to sense a first voltage difference between a first node of the resistive element and a reference voltage, the first transconducting device further configured to transform the first voltage difference into a first output current of the first transconducting device such that the first output current is not dependent upon any other terminal voltages of the transconducting device;
• and
• a second transconducting device coupled to the resistive element, the second transconducting device configured to sense a second voltage difference between a second node of the resistive element and the reference voltage, the second transconducting device further configured to transform the second voltage difference into a second output current of the second transconducting device such that the second output current is not dependent upon any other terminal voltages of the transconducting device.

A method for determining a value of electrical resistance, the method comprising:

• forcing two or more values of known current through a resistor under test to produce two or more voltages generated across the resistor;
• adding each of the two or more voltages generated across the resistor to an adjustable constant voltage, thereby producing two or more voltage sums;
• separately applying each of the voltage sums to an input of a transconducting device;
• generating a current from the transconducting device based on teach of the applied voltage sums, the generated current varying exponentially with the applied voltage sum;
• measuring each of the values of current generated by the transconducting device at two or more values of the known resistor current;
• and
• calculating the value of electrical resistance from the resistor under test from each of the measure values of current generated by the transconducting device at two or more values of the known resistor current.