Dual-Band Transmitter for Wireless Power Transfer to Biomedical Implant Applications

This letter presents a dual-band transmitter (DB-Tx) for wireless power transfer to biomedical implants. The DB-Tx operates at $\text{1.7}\,\text{GHz}$ (LF-band) and $\text{2.1}\,\text{GHz}$ (HF-band) to power implantable devices in deep and shallow implantation, respectively. A bipolar concentric loop (BCL) radiating plane is employed to obtain field-focusing characteristics at dual frequencies, and hence enhance the power transfer efficiency (PTE). Furthermore, a wideband implantable receiver (Rx) is implemented to verify DB-Tx's performance. Experimental results show that, by utilizing the DB-Tx, the transmission range can be extended three times in HF-band and 30% in LF-band, compared with the Tx operating at a single frequency band. The Rx can receive power with the PTE of $-\text{14.7}\,$ and $-\text{23}\,\text{dB}$ at $\text{10}\,$ and $\text{40}\,\text{mm}$ implantation depth, respectively.