26.3 A 1.3nJ/b IEEE 802.11ah fully digital polar transmitter for IoE applications

This paper presents an ultra-low-power (ULP) IEEE 802.11ah fully-digital polar transmitter (TX). IEEE 802.11ah is a new Wi-Fi protocol optimized for Internet-of-Everything (IoE) applications. Compared to other IoE standards like Bluetooth or ZigBee, its sub-GHz carrier frequency and mandatory modes with 1MHz/2MHz channel bandwidths allow devices to operate in a longer range with scalable data-rates from 150kb/s to 2.1Mb/s. Moreover, the use of OFDM improves link robustness against fading, especially in urban environments, and achieves a higher spectral efficiency. The key design challenges of an IEEE 802.11ah TX for IoE applications are to meet the tight spectral mask and error-vector-magnitude (EVM) requirements as for conventional Wi-Fi standards (e.g., 802.11n/g), while achieving low power consumption required by IoE applications. The presented TX applies a fully-digital polar architecture with a 1V supply, and it achieves more than 10× power reduction compared to the state-of-the-art OFDM transceivers [1–4]. Without any complicated PA pre-distortion techniques as in [5], it passes all the PHY requirements of the mandatory modes in IEEE 802.11ah with 4.4% EVM, while consuming 7.1mW with 0dBm output power.