A Multichannel Injection-Locked OOK Transmitter With Current Mode Edge-Combining Power Amplifier

Abstract

This letter introduces an ultralow-power ON–OFF keying (OOK) wireless transmitter incorporating innovative multiphase injection locking and frequency multiplication techniques. The transmitter leverages a current mode class-D edge-combining power amplifier, ensuring high-energy efficiency in frequency multiplication to generate the carrier frequency. With a primary focus on facilitating multichannel support for Internet of Things (IoT) applications, the prototype incorporates a low-frequency phase-rotation-based frequency synthesizer. To mitigate the quantization noise in $\Delta \Sigma $ modulator of the synthesizer, the design combines an N-path filter and injection-locked ring oscillators to effectively filter out the shaped far-out phase noise. The prototype, fabricated in TSMC 90-nm CMOS, achieves an output power of −6.9 dBm with a power consumption of $890~\mu \text{W}$ at a 0.75-V supply voltage. It supports data rates of up to 40 Mb/s under OOK modulation, resulting in an energy efficiency of 22 pJ/bit and a global efficiency of 23%, showcasing its effectiveness in balancing performance and power consumption.