A 14–50-GHz Phase Shifter With All-Pass Networks for 5G Mobile Applications

Abstract

In this work, an ultra-broadband phase-shifter (PS) with a 14-50 GHz bandwidth (defined by a phase-error below 1/2 LSB) is presented to address the multi-band requirements of 5G milimeter-wave (mm-wave) systems. The PS construction is based on all-pass networks (APNs), which have shown broad bandwidth capabilities in a lower frequency range. Aiming towards 5G mobile applications, the proposed 2-bit, 45 • phase resolution PS was implemented in 0.25 µm BiCMOS, manufactured and measured, achieving an insertion loss (IL) of 7.4 ± 0.26 dB at 28 GHz and 10 ± 0.22 dB at 39 GHz, with an RMS gain and phase error < 0.27 dB and < 4 • from 24-30 GHz, respectively, and < 0.33 dB and < 6 • from 37-43.5 GHz, demonstrating its capabilities to cover the 5G mm-wave spectrum. Index Terms-All-pass networks (APN), beamforming, broadband, milimeter-wave (mm-wave), multi-band, phase-array transceivers, switched-type phase-shifter (STPS), 5G.

Variable-Phase All-Pass Network Synthesis and Its Application to a 14–54 GHz Multiband Continuous-Tune Phase Shifter in Silicon

“…In [26], the synthesis was fine-tuned to improve circuit feasibility of APNs, focusing on even-order networks. In [5] we adapt the synthesis procedure to allow multiple APNs in parallel, not possible with Darlington and Orchard's method. In this work, we make further changes to the method to allow the synthesis of two or more APNs with the same inductor values, which is a crucial aspect in the VP-APN design.…”

“…Its continuous-tune capabilities allow its use on several applications, from 5G basestations to satellite phased-arrays. The implementation here differs significantly from our previous work in [5], which used purely passive networks and focused on 5G mobile applications, having only coarse 45 • phaseshifting states.…”

“…Multi-band building blocks allow intellectual property (IP) reuse, therefore reducing time-to-market [4]. Despite these advantages, current wideband/multi-band phase-shifter solutions are still extremely limited [5]- [7], especially when fine phase-shifting resolution is required.…”

“…Among the wide range of phase-shifter topologies [8], Switched Type Phase-Shifters (STPSs) appear to be the best candidate for multi-band capabilities [5], [9]. This is mainly because switches are typically broad-band devices [10], [11], as opposed to 90 • hybrid couplers used in Reflection Type Phase-Shifters (RTPSs) [12].…”

“…The multi-band capacity is then limited by the implementation of the phase-shifting paths. Typical implementations use High-Pass/Low-Pass [13], Bypass/Low-Pass [9], Bypass/All-Pass [14], [15] and All-Pass/All-Pass filters [5], [16]- [19], with the latter showing excellent bandwidth capabilities.…”