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As single tunneling magnetoresistive (TMR) sensor performance in modern high-speed applications is limited by breakdown voltage and saturation of the sensitivity, for higher voltage applications (i.e., compatible to 1.8 V, 3.3 V or 5 V standards) practically only a series connection can be applied. Thus, in this study we focused on sensitivity, 3 dB bandwidth and sensitivity-bandwidth product (SBP) dependence on the DC bias voltage in single and series-connected TMR sensors. We show that, below breakdown voltage, the strong bias influence on sensitivity and the 3 dB frequency of a single sensor results in higher SBP than in a series connection. However, the sensitivity saturation limits the single sensor SBP which, under 1 V, reaches the same level of 2000 MHz·V/T as in a series connection. Above the single sensor breakdown voltage, linear sensitivity dependence on the bias and the constant 3 dB bandwidth of the series connection enable increasing its SBP up to nearly 10,000 MHz·V/T under 5 V. Thus, although by tuning bias voltage it is possible to control the sensitivity-bandwidth product, the choice between the single TMR sensor and the series connection is crucial for the optimal performance in the high frequency range. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of current monitoring in resonant power converters for overcurrent protection. Since the demand for higher power density suppliers is constantly growing, resonant power converters (RPC) have been receiving more and more attention recently, due to its high efficiency and high switching frequency capability. However, to make practical use of this approach there are still crucial issues, such as overcurrent protection of converter components. Therefore, it is required to implement dedicated protection methods based on a quick feedback loop and additional, modern design solutions. To ensure high reliability of any protection method, as well as to implement new solutions in power electronics, novel current monitoring techniques and sensors are needed. Thus, in this study we present high fidelity magnetoresistive current sensors for monitoring MHz signals with extremely low nonlinearity (< 0,015%), hysteresis (close to 0%) and phase shift (close to 0°). The remarkable effectiveness of the proposed sensors was confirmed by monitoring three different, MHz current waveforms, typically occurring in RPCs with different overcurrent protection methods FFT results clearly emphasize superb signal reproduction, which enables the using of the tested sensors in modern high speed, power electronics applications. [ABSTRACT FROM AUTHOR]