Compact and Efficient FSK‐CDR Design for Forward Data Transfer Over Wireless Inductive Link

ABSTRACT Frequency shift keying (FSK) is a robust modulation scheme widely used in biomedical implants for wireless power and data transfer over inductive links due to its low sensitivity to amplitude noise and coil misalignment. However, conventional FSK modulation faces challenges in achieving high data rates and low power consumption, as it requires multiple modulation cycles to encode data bits (0 or 1), limiting carrier utilization. This paper proposes a novel FSK modulation scheme for clock and data recovery (CDR) that minimizes the required number of cycles to encode data bits, improving data rate and reducing power consumption. Using only two and one modulation cycles enables efficient data transmission at higher rates with lower energy usage, offering a promising solution for forward data communication. A prototype FSK modulator and CDR circuit are designed to implement this approach using 0.18 μm CMOS process. The proposed circuit recovers clock and data signals from a FSK‐modulated signal at rates up to 4 Mb/s and occupies an active area of 0.002747 mm 2 (67 μm × 41 μm). The circuit consumes 15.4 μW power from a 1.4 V supply for data transfer. The design achieves an energy efficiency of 3.5 pJ/bit and demonstrates an improved data rate‐to‐carrier frequency (DRCF) ratio and greater compactness than existing FSK demodulators. These features make it suitable for wireless data transfer in energy‐constrained biomedical applications.