In the rapidly evolving landscape of the Internet of Things (IoT), power efficiency and reliable connectivity are paramount. A groundbreaking study published in the journal ‘Sensors’ (translated from Korean as ‘감지기’) introduces a low-power CMOS receiver designed to meet these critical demands, particularly for IoT applications in the 2.4 GHz band. Led by Nam-Seog Kim from the Department of Information and Communication Engineering at Chungbuk National University in South Korea, this research could revolutionize the way we think about wireless communication in energy-sensitive environments.
The heart of this innovation lies in a complex continuous-time delta-sigma analog-to-digital converter (ADC), optimized for Bluetooth Low Energy (BLE) standards. This ADC, integrated into a low-IF (intermediate frequency) architecture, achieves an impressive effective number of bits (ENOB) of 10.9 while consuming a mere 0.81 mW from a 1.0 V supply. “The key challenge was to balance power efficiency with high performance,” explains Kim. “Our design not only meets but exceeds the stringent requirements of modern IoT applications.”
The receiver demonstrates remarkable performance metrics, including a sensitivity of −95 dBm at a 10⁻3-bit error rate, an image rejection ratio of 54.2 dBc, and a spurious-free dynamic range of 79.8 dBc. Operating at a 1.5 MHz intermediate frequency with a 2 MHz bandwidth, the ADC achieves superior energy efficiency with a figure of merit (FOMW) of 103.2 fJ/conv. This level of efficiency is crucial for battery-powered IoT sensor nodes, where longevity and reliability are non-negotiable.
The implications for the energy sector are profound. As IoT devices proliferate, the need for low-power, high-performance wireless communication solutions becomes ever more pressing. This receiver design addresses these needs head-on, offering a compact, energy-efficient solution that can be integrated into a wide range of applications, from smart grids to industrial automation.
One of the standout features of this design is its ability to handle multiple communication protocols with adaptable modulation schemes and data rates, all while maintaining low power consumption. This flexibility is essential in the evolving IoT ecosystem, where devices must be versatile and efficient.
The design also incorporates several innovative techniques, such as a thermometer-coded capacitor array layout for improved matching, DWA-based linearization for the feedback DAC, and an RC calibration scheme that maintains accurate frequency response across process, voltage, and temperature variations. These optimizations collectively result in a power-efficient receiver that is particularly suitable for battery-operated IoT sensor nodes in the 2.4 GHz band.
The complete receiver system, implemented in 28 nm CMOS technology, occupies just 0.375 mm² for the RF front-end and 0.145 mm² for the ADC, making it an ideal candidate for space-constrained IoT devices. “Our goal was to create a receiver that is not only powerful but also compact and cost-effective,” says Kim. “We believe this design sets a new standard for IoT communication.”
As the IoT continues to expand, the demand for such innovative solutions will only grow. This research, published in ‘Sensors’, paves the way for future developments in low-power wireless communication, offering a blueprint for the next generation of energy-efficient IoT devices. The energy sector, in particular, stands to benefit greatly from these advancements, as reliable and efficient wireless connectivity becomes increasingly vital. The future of IoT is here, and it’s more energy-efficient than ever before.