I. Introduction
The rapidly increasing demand for high-data-rate wireless communication has motivated research of millimeter-wave (mm-Wave) circuits and transceivers [1]. In recent years, 28-GHz band (n257, n258, n261) has been licensed by 3GPP as an extension of the sub-6 GHz frequency range for the fifth-generation (5G) wireless communication [2]. Besides, V band also has been promoted for IEEE 802.11ad/WiGig very-high-throughput (VHT) wireless local area networks (WLANs) [3]. To be compatible with different standards and lower the cost of wireless system deployment, mm-Wave transceiver front-ends which can support multiple bands have attracted tremendous attention from academic and industrial fields [4], [5], [6], [7], [8].