An Open-Loop Double-Carrier Simultaneous Wireless Power and Data Transfer System

In this brief, an open-loop double-carrier simultaneous wireless power and data transfer system is presented. Although the system is intended for implantable biomedical microsystems, it can also be used for other low-power applications such as Internet of Things (IoT). In the proposed system, uplink data communication (from the implant to the outside of the body) is implemented by switching a capacitor on the implant site. This switching results in changing the resonance frequency between two different frequencies during different periods of time. To keep the power transfer efficiency (PTE) and the power delivered to the load (PDL) almost constant, two external power transmitters, each working at its own distinct frequency, are employed. The closed-loop control unit, which is commonly used to synchronize the timing between transmitter and receiver, is avoided to enhance the overall performance, including the data rate and efficiency, and to reduce the complexity of the system. In a proof-of-concept prototype, about 44 mW of power is transmitted to a 750 ${{\Omega }}$ resistive load over ${f_{1} = 1.93}$ MHz and $ {f_{2} = 1.44}$ MHz with an average efficiency of 39%. A data rate of 50 kb/s has also been achieved for the uplink telemetry.