Abstract
This article presents an efficient digital polar transmitter (DPTX) at mm-wave frequencies that exploit a novel N -way series Doherty combiner (SDC) to enhance its drain and system efficiency at deep power back-off (PBO). The proposed N -way SDC is scalable and can be implemented elegantly using N transformers and N-1 shunt capacitors. As a proof of concept, a four-way Doherty DPTX is realized with the proposed SDC in which four identical but independent digital phase modulators deliver a phase-modulated constant envelope signal to their corresponding digital power amplifiers to perform the required amplitude modulation. Fabricated in a 40nm CMOS process, the proposed DPTX occupies a core area of 1.1 mathrm {mm^{2}} and exhibits 18.7dBm saturated output power and <-40dBc LO feedthrough. It demonstrates a drain efficiency of 33%/36%/22% at 0/4.5/11.5dB PBO at a 29.5GHz carrier frequency. While transmitting a 300MHz 64-QAM OFDM signal with a peak-to-average power ratio of 10.7dB, the DPTX achieves 18%/8% average drain/system efficiency, -27.6dB error vector magnitude, and -27.5dBc adjacent channel leakage ratio. To the best of our knowledge, this work is the first reported mm-wave Doherty transmitter that includes the entire chain all the way from the binary data stream up to the modulated mm-wave output signal.
Original language | English |
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Article number | 9675289 |
Pages (from-to) | 803-817 |
Number of pages | 15 |
Journal | IEEE Journal of Solid-State Circuits |
Volume | 57 |
Issue number | 3 |
DOIs | |
Publication status | Published - 2022 |
Bibliographical note
Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-careOtherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.
Keywords
- Digital phase modulator (DPM)
- digital polar transmitter (DPTX)
- digital power amplifier (DPA)
- Doherty design guide
- millimeter-wave transmitter (TX)
- power amplifier (PA)
- series Doherty combiner (SDC).