A Fully SiP Integrated $V$-Band Butler Matrix End-Fire Beam-Switching Transmitter Using Flip-Chip Assembled CMOS Chips on LTCC

Abstract

In this paper, a fully system-in-package (SiP) integrated <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> -band Butler matrix beam-switching transmitter (TX) is presented. The CMOS chips from differential process technologies are assembled on a low-temperature co-fired ceramic (LTCC) substrate carrier by flip-chip interconnects. The vertically embedded folded monopole antenna is designed and integrated into the LTCC. The array consisting of four identical monopole antennas and a Butler matrix for beam switching is realized on the LTCC for loss reduction. Four switched main beams are measured and agree well with simulation. This beam-forming TX shows the potential of the low-cost millimeter-wave SiP with CMOS chips.