Is Power Electronics Outgrowing the Shunt Resistor?

For decades, the shunt resistor has been the default tool for current sensing, prized for its simplicity and grounding in Ohm's Law. But as GaN and SiC push switching frequencies into the megahertz range, and systems shrink while demanding more power, shunts are hitting real limits.

The Hidden Costs of Shunt Resistors

The problems compound quickly. Heat rises quadratically with current, board space grows to manage that heat, and shunts require a supporting cast of amplifiers, filters, and precise layouts. On 48-V rails, common in EVs, robotics, and AI server racks, shunts also need costly high-voltage amplifiers that can struggle against aggressive voltage swings.

A Different Approach: Magnetic Current Sensing

Magnetic current sensing offers a different path. Integrated magnetic sensors combine conductor, sensing element, and signal conditioning into one calibrated package, cutting power loss by up to 90% and board space by up to 95%. For higher currents, coreless sensors handle hundreds or thousands of amps without bulky cores.

TMR: Closing the Noise Gap

The real breakthrough is tunnel magnetoresistance (TMR) technology, which produces a much stronger signal than traditional Hall-effect sensors. This means lower noise, better resolution, and bandwidths up to 10 MHz, fast enough to protect wide-bandgap switches from overcurrent faults in nanoseconds.

The question is no longer whether to use a shunt or not. Instead, it's "what's the right current sensor for this specific job?"

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