A Compact 26.5–29.5-GHz LNA-Phase-Shifter Combo With 360° Continuous Phase Tuning Based on All-Pass Networks for Millimeter-Wave 5G

Abstract

This article presents a compact integrated receiver front-end for phased-arrays at 5G n257/n261 band (26.5–29.5 GHz) employing both a low-noise amplifier (LNA) and a novel passive phase-shifter based on variable-phase all-pass networks. The proposed phase-shifter topology is analysed and designed using $0.25~\\mu \\text{m}$ BiCMOS achieving continuous tuning capabilities with 360° phase range over a 25–33 GHz frequency range under 0.1 mm2 of area. The proposed phase-shifter is measured standalone, achieving 8.3 ± 0.55 dB losses at 29 GHz with an RMS gain error below 0.6 dB across the entire frequency range. When quantizing the continuous phase-shift into 6 bits, an RMS phase error < 3° is obtained. To build the LNA-Phase-shifter combo, the phase-shifter is then integrated with an LNA optimized for compactness, which was measured standalone, showing a noise figure below 3.2 dB across the n257/n261 band and 20 dB gain under 0.0625 mm2 of area. The small size of both the phase-shifter and LNA enables an ultra-compact phased-array receiver front-end under 0.2 mm2 of area. The front-end is measured, achieving 11.5 ± 0.53 dB of gain, RMS gain error below 0.42 dB and RMS phase error below 3.2° over the entire n257 band, measured input-referred P1dB of −25 dBm and a 15 mW DC power consumption.