Method and circuit arrangement for determining a resistance

A method of determining a resistance of a first transistor in a drive system for operating a motor, the drive system comprising a plurality of transistors, and each transistor of the plurality of transistors comprising a control terminal, a first channel terminal, and a second channel terminal, the method comprising:

• switching the plurality of transistors to operate the motor using an operating current, wherein current is configured to flow between the first and second channel terminals of each transistor in an on-state such that the operating current flows between motor coils of the motor and a reference node, and wherein the reference node is shared by each of the plurality of transistors;
• applying a test current between the first and second channel terminals of the first transistor during the on-state of each of the plurality of transistors, wherein the test current applied at a current value;
• measuring a voltage difference between the first and second channel terminals of the first transistor during application of the test current;
• and
• determining the on-state resistance of the first transistor based on the current value and the measured voltage difference.