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High-speed, low-power optical interconnects, such as intensity modulation direct detection (IMDD) optical links, are increasingly deployed in data centers to keep pace with the growing bandwidth requirements. High-sensitivity low-power optical receivers (RXs) are the key components that enable energy-efficient IMDD optical interconnects. This article presents a low-power nonreturn-to-zero (NRZ) optical RX using a combination of a limited-bandwidth trans-impedance amplifier (TIA) and duobinary sampling to improve RX sensitivity at high data rates. Duobinary sampling leverages the well-controlled TIA inter-symbol interference (ISI) to recover the transmitted data, making it much more hardware efficient than canceling the ISI using a decision feedback equalizer (DFE). The proposed optical RX employs a CMOS-based analog front-end (AFE) to achieve high linearity and excellent power efficiency. Fabricated in 65-nm CMOS process, the prototype RX achieves optical modulation amplitude (OMA) sensitivity of −11.6 dBm at 16 Gb/s with 0.7-pJ/bit efficiency.

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In this study, a high-efficiency wireless power transfer (WPT) coil that is robust against interoperability and misalignment was developed by applying an inductive power transfer system to a drone. The transmitting coil had a ferrite plate applied to a helical structure that included the receiving part. The receiving coil was a guard-type receiving part applied to the ferrite sheet. To analyze the spiral and helical coils according to the winding method, the z-axis magnetic field vector was analyzed. A suitable WPT model was developed for each drone by analyzing the mutual inductance based on whether the ferrite was attached to the transmitter or receiver and the ferrite sheet's location. The electrical characteristics of the coil were derived using Ansys Electronics Maxwell, and a comparative analysis was performed using the measured values of the fabricated coil. The mutual inductance change due to misalignment between the coils of the transmitter and receiver of the proposed model was analyzed. It was demonstrated that the magnetic field distribution was uniform according to the misalignment error.