Energy-efficient optical receivers for the Internet of Things

Energy-efficient optical receivers for IoT leverage low-power transimpedance amplifiers, advanced equalization, and optimized modulation schemes to achieve high sensitivity with minimal energy per bit.Key Design TechniquesTransimpedance Amplifiers (TIA): Low-power TIAs are central to energy-efficient optical receivers. Designs often use shunt-feedback (SF) or transadmittance-stage topologies to reduce thermal noise and maintain linearity while minimizing power consumption . Multi-stage TIAs can improve sensitivity without increasing silicon area or power . Equalization Methods: Sensitivity enhancement is achieved using continuous-time linear equalizers (CTLE), feed-forward equalizers (FFE), and decision feedback equalizers (DFE). These techniques mitigate inter-symbol interference (ISI) and improve data recovery, allowing receivers to operate efficiently at higher data rates . Modulation Schemes: For IoT and short-reach applications, NRZ, PAM-4, and duobinary sampling are commonly used. Duobinary sampling, in particular, improves sensitivity and energy efficiency by leveraging controlled ISI rather than canceling it, enabling higher data rates with lower power . PAM-4 receivers can achieve high data throughput while maintaining low energy per bit, e.g., 1.28 pJ/bit at 48 Gb/s .Integration and FabricationCMOS and 3D Integration: Fabrication in advanced CMOS nodes (28 nm, 12 nm) allows for ultra-low-power operation and high bandwidth density. 3D integration with co-designed optical devices further reduces power consumption and improves sensitivity, achieving sub-100 fJ/bit efficiency in state-of-the-art designs . Wire-bonded photodetectors and micro-ring resonators are also used to bridge optical and electrical domains efficiently . DSP-Free Architectures: To reduce power, some designs eliminate digital signal processing (DSP) at the receiver, using linear pluggable optics (LPO) or linear receiver optics (LRO) architectures. These approaches achieve significant power reductions (up to 73%) while maintaining high-speed optical-to-electrical conversion .Performance MetricsSensitivity: Optical modulation amplitude (OMA) sensitivity ranges from -5.1 dBm to -17 dBm depending on the design and modulation scheme .Energy Efficiency: Modern designs achieve 0.27–0.84 pJ/bit for the TIA alone and overall receiver efficiencies below 100 fJ/bit in advanced 3D-integrated systems .Data Rates: Short-reach receivers for IoT can operate from 12 Gb/s to 48 Gb/s, with higher aggregate rates possible in multi-channel 3D-integrated transceivers .Practical Implications for IoTEnergy-efficient optical receivers are particularly suitable for IoT networks requiring low-power, high-density, and short-reach communication, such as data centers, sensor networks, and edge devices. By combining low-power TIAs, optimized equalization, and efficient modulation, these receivers minimize energy consumption while maintaining reliable data transmission, enabling scalable and sustainable IoT deployments.