A hybrid bandwidth expansion method based on load resistor and high-pass filter for tunnel magnetoresistance current sensors

The bandwidth of tunnel magnetoresistance (TMR) current sensors is constrained by the parasitic capacitance within the TMR chip, which severely limits their applicability in high-frequency domains such as wide-bandgap power electronics. Existing bandwidth expansion techniques often necessitate modifications to the conductor geometry or integration with auxiliary devices like Rogowski coils, which exhibit limitations such as modest effectiveness and intricate signal conditioning circuitry. This article presents a hybrid approach employing load resistors and high-pass filters to extend the bandwidth by reducing the equivalent resistance of the TMR chip and compensating its inherent low-pass behavior. Experimental results demonstrate that the proposed method enhances the TMR sensor bandwidth by a factor of 11.5, from 193.7 kHz to 2.23 MHz. Concurrently, the sensor’s resolution, accuracy, and response speed are markedly improved. A key advantage of this method is its ability to achieve substantial bandwidth extension without altering the conductor geometry or requiring complex processing circuits.