Adel Barakat

Wireless power transfer (WPT) has emerged as a promising technology for modern implantable medical devices (IMDs), providing a reliable alternative to traditional batteries and reducing the need for repeat surgical procedures. WPT-based IMDs are extensively employed in biomedical applications such as deep brain stimulators, endoscopic capsules, pacemakers, and cardiac monitoring systems, which are being commercialized. As the IMD market is expected to grow with the aging population, extensive research efforts are proceeding to address key design and implementation challenges. A key challenge lies in simultaneously achieving high power-transfer efficiency (PTE), high data rates, low power consumption, and low circuit complexity. This review paper thoroughly examines recent developments, design trends, and current research problems in simultaneous power and bidirectional data transmission over a single inductive link, as well as the associated modulation and demodulation techniques. We reviewed various uplink and downlink modulation techniques, focusing on key characteristics such as data rate, power consumption, circuit complexity, and health and safety considerations. Finally, future research directions toward efficient, compact, and reliable simultaneous wireless power and data transfer (SWPDT) for the next generation of IMDs are discussed. This review paper will hopefully guide ongoing research into more efficient, scalable, and safe SWPDT systems.

Wireless power transfer using beamforming technology has recently gained significant attention for sensor networks and embedded systems. This technology uses array antennas and mid-range RF power (15–20 dBm) rectifiers for efficient power delivery to sensors. Despite its potential, research on mid-range RF power CMOS rectifiers remains limited. Addressing this gap, we propose a high-efficiency pMOS-based rectifier employing a body-biasing technique—a proven method for enhancing device performance—specifically designed for wideband and mid-range RF power RF applications. Conventional rectifiers often depend on precise input impedance matching to achieve high power conversion efficiency (PCE), which restricts bandwidth and limits practicality in dynamic environments. To overcome these challenges, the proposed design integrates a modified matching network, combined with dynamic body-biasing, which lowers the pMOS threshold voltage and minimizes power losses. Simulations reveal a peak PCE of 60.5%, with efficiency exceeding 50% across a broad frequency range up to 2.5 GHz—significantly outperforming traditional designs. Unlike conventional impedance-matching solutions, this rectifier maintains robust performance under input mismatches, making it well-suited for beamforming-based WPT systems. This study highlights the potential of integrating body-biasing with advanced matching networks for efficient wideband rectifiers.

The use of multi-band matching for rectifiers leads to design complexity. Instead, recent advancements suggested self-matched branches combined in parallel to enable multi-band operation. However, this method controls only the imaginary part. In this paper, we propose an efficient dual-band rectifier with compact realization. The rectifier consists of two self-matched parallel branches. Each branch provides comprehensive impedance control over real and imaginary parts in the corresponding band independent of the design frequency. The branch impedance matching is analyzed theoretically, and design equations are presented. To verify the proposed theory, a compact dual-band rectifier was fabricated with a compact area of only 0.42 cm² after excluding the area required for the RF connector. The measured RF-DC power conversion efficiency (PCE) was >50% for input power (P_in) ranging from −5.5 dBm to 11 dBm at 390 MHz with a peak of 69%. Also, the PCE was >50% for P_in ranging from −4 dBm to 12 dBm at 690 MHz with a peak of 68%. The fabricated rectifier operates with a wide load range from 0.5 KΩ to 3 KΩ with PCE > 50% at both bands when P_in = 5 dBm.

The use of multi-band matching for rectifiers leads to design complexity. Instead, recent advancements suggested self-matched branches combined in parallel to enable multiband operation. However, this method controls only the imaginary part. In this letter, we propose an efficient dual-band rectifier with compact realization. The rectifier consists of two self-matched parallel branches. Each branch provides comprehensive impedance control over real and imaginary parts in the corresponding band independent of the design frequency. The branch impedance matching is analyzed theoretically, and design equations are presented. To verify the proposed theory, a compact dual-band rectifier was fabricated with a compact area of only 0.42 cm2 after excluding the area required for the RF connector. The measured RF-DC power conversion efficiency (PCE) was > 50% for input power (Pin) ranging from -5.5 dBm to 11 dBm at 390 MHz with a peak of 69%. Also, the PCE was > 50% for Pin ranging from -4 dBm to 12 dBm at 690 MHz with a peak of 68%. The fabricated rectifier operates with a wide load range from 0.5 KΩ to 3 KΩ with PCE > 50% at both bands when Pin=5 dBm.

This paper presents an efficient wideband data recovery circuit (DRC) for forward data transfer in the over-coupled mode of dynamic SWPDT systems. In the over-coupled mode, where the operating frequency varies, conventional DRCs often become ineffective due to their limited operating frequency range. To address this issue, we propose a wideband DRC using amplitude shift keying (ASK) with on–off keying (OOK) modulation. The proposed circuit also eliminates the need for diodes and averaging circuits, which are typically required in traditional designs. The proposed circuit achieves data recovery by passing the OOK-modulated signal through a proposed Voltage-to-Time Converter (VTC), followed by a comparator and inverter. Implemented in 180 nm CMOS technology, the circuit occupies an area of 2440 μm² and a power consumption of 52.08 μW. The circuit can operate across a wide range of carrier frequencies. It was tested and validated with OOK-modulated signals at 5 MHz, 50 MHz, and 150 MHz, confirming its versatility and robustness. The prototype circuit enables wireless data transmission in critically coupled, weakly coupled, and over-coupled modes of WPT systems, achieving a 2 Mb/s data rate without requiring receiver repositioning.

The use of multi-band matching for rectifiers leads to design complexity. Instead, recent advancements suggested self-matched branches combined in parallel to enable multiband operation. However, this method controls only the imaginary part. In this letter, we propose an efficient dual-band rectifier with compact realization. The rectifier consists of two self-matched parallel branches. Each branch provides comprehensive impedance control over real and imaginary parts in the corresponding band independent of the design frequency. The branch impedance matching is analyzed theoretically, and design equations are presented. To verify the proposed theory, a compact dual-band rectifier was fabricated with a compact area of only 0.42 cm2 after excluding the area required for the RF connector. The measured RF-DC power conversion efficiency (PCE) was > 50% for input power (𝑷𝒊𝒏) ranging from -5.5 dBm to 11 dBm at 390 MHz with a peak of 69%. Also, the PCE was > 50% for 𝑷𝒊𝒏 ranging from -4 dBm to 12 dBm at 690 MHz with a peak of 68%. The fabricated rectifier operates with a wide load range from 0.5 KΩ to 3 KΩ with PCE > 50% at both bands when 𝑷𝒊𝒏 = 𝟓 dBm.

This letter introduces a novel approach to achieve high efficiency in high-power rectification using 180-nm complementary metal–oxide–semiconductor (CMOS) technology. The proposed rectifier targets the utilization of electromagnetic waves within the platinum band, operating within the frequency range of 0.6–0.9 GHz. Unlike conventional body-biasing techniques using pMOS transistors, where the output terminal is used for biasing, the proposed method employs biasing through the drain voltage of respective transistor. This approach results in higher output voltage for increased input power. Measurement results demonstrate outstanding power conversion efficiency (PCE) exceeding 60% and an output voltage surpassing 9 V across the 0.6–0.9 GHz range at 16-dBm input power ( ${P}_{\text{in}})$ . Furthermore, the peak PCE of 67.5% was achieved at a carrier frequency of 0.7 GHz.