K/Ka-Band Hybrid-Packaged Four-Element Four-Beam Phased-Array Transmitter and Receiver Front-Ends With Optimized Beamforming Passive Networks
Mengru Yang, Dixian Zhao, Chenyu Xu, Peng Gu, Yongran Yi, Mohan Guo, Xiangxi Yan, Liangliang Liu, Yuan Chai, Huiqi Liu, Xiaohu You
Abstract
This article presents K/Ka-band four-element four-beam phased-array transmitter (TX) and receiver (RX) front-ends. Hybrid-packaged technology is employed, consisting of one TX/RX 65-nm CMOS beamformer and four 0.1- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m GaAs power amplifiers (PAs)/low-noise amplifiers (LNAs). Each beam maintains a full connection to every antenna element without degrading array gain. A compact and symmetrical layout floor-plan is proposed to reduce signal routing complexity. Signal distribution and combination are performed through two optimized tree-type and rectangular-shaped beamforming networks to improve the beam-to-beam consistency and isolation. The TX/RX CMOS beamformer provides an energy-efficient solution by adopting low-power phase/amplitude controls. The second harmonic trap is co-optimized with the transformer-based matching to enhance linearity in the TX. A new L-type inductor-enhanced matching network is devised in the RX to broaden bandwidth. In addition, the digital circuit introduces a voting mechanism to improve fault tolerance. Utilizing fan-out wafer-level chip-scale packaging, both hybrid-packaged TX and RX front-ends occupy an area of 50 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^\text{2}$</tex-math> </inline-formula> . The proposed TX demonstrates a measured small-signal gain of 23.5–26.5 dB across 17.7–20.2 GHz. The output 1-dB compression point ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P_\text{1\,dB}$</tex-math> </inline-formula> ) and the maximal power-added efficiency (PAE <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_\text{MAX}$</tex-math> </inline-formula> ) reach 21.2–23.2 dBm and 26%–30%, respectively. The proposed RX achieves a measured average gain of 24 dB across 27.5–30 GHz with a minimal noise figure (NF) of 3.1 dB. Both TX and RX exhibit uniform performance across all channels, while consuming a maximal power of 2600 and 264 mW, respectively, equivalent to 162.5–16.5 mW per element per beam.