Discrete Low-Cost Implementation of Inductive Energy and Data Transmission for Deeply Integrated Sensor Systems

This paper presents a flexible, low-cost concept for inductive energy and data transmission. It is implemented using discrete commercial-of-the-shelf components and allows reconfiguring the operating frequency and the data transmission protocol. Amplitude shift keying is used as the modulation scheme. To efficiently de- and encode the data stream, the programmable logic elements of a SiLabs EFM8-LB microcontroller are utilized. The prototype system achieves an error-free data rate of 72 kBit/s and a power transfer of 145mW with up to 7mm distance between primary and secondary coil. The power is sufficient to drive a 120Omega strain gauge, while the data rate is high enough to fully utilize a ADS1220 integrated sensor interface with 2000 S/s at 24 Bit resolution.