A 1.3 nJ/b IEEE 802.11ah fully-digital polar transmitter for IoT applications

Ao Ba, Yao Hong Liu, Johan van den Heuvel, Paul Mateman, Benjamin Busze, Johan Dijkhuis, Christian Bachmann, Guido Dolmans, Kathleen Philips, Harmke de Groot

Research output: Contribution to journalArticleAcademicpeer-review

24 Citations (Scopus)


A 1.3 nJ/b IEEE 802.11ah TX for IoT applications is presented. A fully-digital polar architecture consisting of an all-digital PLL-based frequency modulator and an AM-retiming Δ Σ switched-capacitor PA (SC-PA) achieves more than 10× power reduction than state-of-the-art OFDM TXs. Several circuit-design techniques such as LSB truncation error feedback are proposed to efficiently pre-process the AM/PM data to improve the TX performance. A design approach of the SC-PA for optimum overall efficiency is introduced. The PLL spur level is reduced to 55 dBc by a switched-capacitor based digital-to-time converter. A dynamic divider is implemented together with a 1.8 GHz oscillator for efficient LO generation. Fabricated in a 40 nm CMOS process, this TX fulfills all the IEEE 802.11ah mandatory-mode PHY requirements with 4.4% EVM and > 4.8 dB spectral mask margin, while consuming 7.1 mW from a 1 V supply when delivering 0 dBm output power.

Original languageEnglish
Article number7551133
Pages (from-to)3103-3113
Number of pages11
JournalIEEE Journal of Solid-State Circuits
Issue number12
Publication statusPublished - 1 Dec 2016


  • IEEE 802.11ah
  • IoT
  • low power
  • OFDM
  • polar transmitter
  • transmitter


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