A 2.6mW 10pTI $\sqrt{}$ Hz 33kHz Magnetoimpedance-Based Magnetometer with Automatic Loop-Gain and Bandwidth Enhancement

Low-noise, $< 100\text{pT}/\sqrt{}\text{Hz}$, and low-power magnetometers are indispensable in compact magnetomyography (MMG) measurement and can be utilized in devices involving human-computer interaction and prosthetic implants [1]. In addition, such applications require a high bandwidth of> 10kHz as fast neuronal magnetic activity should be acquired close to the skeletal muscle directly. This paper presents a 2.6mW magnetometer with $10\text{pT}/\sqrt{}\text{Hz}$ input-referred noise and 33kHz signal bandwidth. The proposed magnetometer adopts a digital calibration scheme that automatically maximizes the loop gain and loop bandwidth with low power consumption for low-noise and high-bandwidth realization. The normalized energy of the proposed magnetometer reaches 1.6pJ, improving power efficiency compared with state-of-the-art designs [2]–[5], while maintaining a low noise characteristic.