A 24-to-30GHz Double-Quadrature Direct-Upconversion Transmitter with Mutual-Coupling-Resilient Series-Doherty Balanced PA for 5G MIMO Arrays

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Abstract

The performance and robustness of millimeter-wave (mm-wave) phased-array transmitters (TXs) define, to a large extent, the quality of a high-data-rate 5G link. In practical situations, however, this TX performance is strongly affected by mutual coupling among the closely-spaced radiating elements in the phased-array antenna, yielding a beam-steering angle-dependent and time-varying loading or VSWR condition. Furthermore, 5G mm-wave systems typically employ spectrally efficient modulation schemes with high peak-to-average power ratios (PAPRs). This requirement demands the TX power amplifier (PA) to operate in power back-off (PBO), thus degrading its average efficiency. To alleviate this issue, outphasing or Doherty PAs (DPAs) can be adopted [1-4]. However, as depicted in Fig. 14.4.1 (Top left), these efficiency-enhancement techniques will worsen the output reflection coefficient of the PA (\Gamma_{{\mathrm {PA}}}). Consequently, the unwanted 'element-to-element' coupled signal reflects back to the antenna and will deteriorate the phased-array beam pattern and its TX linearity. A previously promoted solution for this antenna VSWR problem is load mismatch detection, followed by tuning of the output matching network (self-healing). However, this requires the use of a reconfigurable and inevitably lossy matching network [5]. Also, active load pulling [1] and using a reconfigurable series/parallel DPA configuration [2] have been proposed to realize a VSWR resilient efficiency-enhanced TX. Nevertheless, all these techniques are only suitable when dealing with a known and stable antenna impedance mismatch, which is, unfortunately, not the case in practical situations.

Original languageEnglish
Title of host publication2021 IEEE International Solid-State Circuits Conference, ISSCC 2021 - Digest of Technical Papers
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Pages223-225
Number of pages3
ISBN (Electronic)9781728195490
DOIs
Publication statusPublished - 2021
Event2021 IEEE International Solid-State Circuits Conference, ISSCC 2021 - San Francisco, United States
Duration: 13 Feb 202122 Feb 2021

Publication series

NameDigest of Technical Papers - IEEE International Solid-State Circuits Conference
Volume64
ISSN (Print)0193-6530

Conference

Conference2021 IEEE International Solid-State Circuits Conference, ISSCC 2021
CountryUnited States
CitySan Francisco
Period13/02/2122/02/21

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