I. Introduction
Microwave and millimeter-wave phased arrays have been demonstrated in silicon-based technologies (SiGe or CMOS) for low-cost wireless communications and radar with better signal-to-noise ratio and higher channel capacity [1], [2]. In millimeter-wave applications (>30 GHz), the silicon-based solutions of phased arrays are even more promising since the chip area can be further reduced due to the increased operating frequency with higher data rate communication. Recently, many research focused on millimeter-wave phased arrays using silicon-based technologies have been demonstrated [2]–[13].