A K-Band Fully-Integrated Multi-Channel Active Antenna-in-Package Module in Low-Temperature Cofired Ceramic

A K-band active antenna-in-package (AiP) module is designed, fabricated, and measured in this communication, which integrates the antenna array and the multi-channel RF receiving front-end circuits in a 3-D stacked manner. The low-temperature cofired ceramic (LTCC) technology is applied, due to its flexibilities of low-loss high-frequency interconnection, embedded passive RF devices, and miniaturized multilayer configuration. The four <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 4$ </tex-math></inline-formula> cross-dipole antenna subarrays are connected with the four RF receiving channels individually through vertical interconnects, with the parasitic effect compensated. The GaAs RF chips and decoupling capacitors are mounted on the bottom surface of the LTCC substrate while the low-pass filters (LPFs) and power combiner are realized directly in LTCC. The fully integrated active AiP module, with a compact size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.77\lambda _{0} \times 1.77\lambda _{0}$ </tex-math></inline-formula>, is mounted on PCB by solder bumps for power supplies and control. Near-field calibration and far-field measurements are carried out for the developed AiP module. It provides a high total gain of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$52.4\sim 54.7$ </tex-math></inline-formula> dB, a low noise figure (calculated) of 1.6 dB, and an axial ratio below 2.2 dB within <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$18\sim 20$ </tex-math></inline-formula> GHz. The beamforming performance is also demonstrated by tuning the phase shifters (PSs) and attenuators (ATTs) with calibration to achieve a scanning range of ±50°. Good agreement is observed between the measured and simulated results, validating the link budget model for the active AiP.