An improved FSK-modulated class-E power and data transmitter for biomedical implants

This paper presents an efficient dual-resonance biomedical inductive link for frequency-shift keying (FSK) modulation. In this link, the combination of PCB coil as the main coil and the solenoid as the compact inductance creates a dual-resonance coil. 3.22 mm of winding diameter in solenoid makes the link suitable for biomedical implants. Using the dual-resonance link, an efficient FSK-modulated power and data transmitter is proposed for biomedical implants to transmit power and data simultaneously with the same carriers and a single inductive link. So, there is no concern about the interference between power and data carriers. Also, the presence of two resonance frequencies at the secondary side of the link significantly improves the efficiency. With a 6 mm air gap and 2.5 Mbps data rate (DR), the measured power delivered to load (PDL) and power transmission efficiency (PTE) are 57.4 mW and 48.4%, respectively. Also, with a 6 mm interface of beef ribs + medical-grade silicone, the measured PDL and PTE are 48.2 mW and 38.8%, respectively. The measured bit error rate (BER) for 2.5 Mbps data rate is less than 10-5.