Simultaneous Magnetic Resonance Wireless Power and High-Speed Data Transfer System With Cascaded Equalizer for Variable Channel Compensation

Wireless power transfer (WPT) systems can potentially provide simultaneous power and data transfer for Internet-of-Things devices, such as smart speakers, glasses, and watches. However, due to the high quality factor of coils, the intrinsically narrow WPT channel bandwidth severely limits the data transmission capability of the system, especially for data downloading links requiring higher data rates. In addition, the channel bandwidth varies with power transfer distances, which is also undesirable for wireless communication. In this study, the channel features of a two-coil series-series matching magnetic resonance wireless power and data transfer (MWPDT) system, including the bandwidth and the roll-off slope are characterized analytically. Based on the characterization results, a receiver front-end circuit with a three-stage cascaded equalizer (EQ) is proposed and implemented to extend the bandwidth of a MWPDT system at different distances. The proposed EQ can provide a frequency response with a variable roll-up slope from 10 to 45 dB/dec to compensate for the distance-dependent channel response of an MWPDT system. A complete MWPDT system is built and tested to verify the performance of the proposed method. Experimental results demonstrate that the data rates can be extended from 650, 500, and 350 kbps to 850, 700, and 650 kbps at 0.4, 0.5, and 0.6-m distances, respectively. The highest data rate extension ratio is 85% at a transmission distance of 0.6 m, which is 2.4 times the radii of the coil employed in the system.