Recent development of microwave systems and applications at National Taiwan University

Abstract

This paper introduces the recent development of microwave systems and applications at National Taiwan University. Several millimeter-wave modules using MMIC chips and system-in-package (SiP) technology have been developed, including two V-band modules for phased-array applications and a pair of W-band transmit/receiver modules, mainly for wireless Gbps data transmission applications. Also, in order to investigate behavior of bees with colony collapse disorder (CCD), a 9.4/18.8 GHz harmonic radar is also developed. Both the design and performance of these systems will be presented. I. 60-GHZ FOUR-ELEMENT PHASED-ARRAY TRANSMIT/RECEIVE SIP MODULES IN 65-NM CMOS PROCESS WITH FLIP-CHIP INTERCONNECTA pair of 60-GHz four-element phased-array transmit/receive (TX/RX) system-in-package (SiP) modules in 65-nm CMOS technology are developed [1]. The design is based on the all-RF architecture with 4-bits RF switching type phase shifters (STPS), phase compensated variable gain amplifier (VGA), 4:1 Wilkinson power combining/ dividing (PC/PD) network, variable gain low noise amplifier (VGLNA), power amplifier (PA), 6-Bits Unary digital-toanalog converter (DAC), bias circuit, electrostatic discharge (ESD) protection, and digital control interface (DCI). The 2×2 TR phased array have been packaged with 4 antennas in a low temperature co-fired ceramic (LTCC) module and phased-array beam steering have been demonstrated. The entire beam steering functions are digitally controllable, and individual registers are integrated at each front-end to enable beam steering through the DCI. The four-element TX array results in an output P 1dB of 5 dBm per channel. The fourelement RX array results in an average gain of 25 dB per channel. The four-element array consumes 400 mW in the TX from 1-V supply voltage and 180 mW in the RX from 1.8-V and 1-V supply voltage, and occupies an area of 3.74 mm 2 in TX IC and 4.18 mm 2 in RX IC. Good agreement between simulated and measured array pattern is demonstrated.The 60-GHz SiP module packaging technology has also been developed. The Tx/Rx ICs are bonded onto LTCC substrates through flip-chip bonding and underfill process, which can be assembled onto printed circuit boards with bond wires or solder balls for further usage. Electrical characteristics of the RF signal traces from IC to antenna array are investigated. To minimize the overall path loss and crosstalk between traces with maximum operating bandwidth, different techniques are proposed for the design of flip-chip compensation, electrically identical fan-out structure, and impedance matched via transition. The antenna array is designed on the other side, opposite to the flipped chips, using the backed cavity to achieve more than 20% bandwidth and isolation design for better array performance. The radiation efficiency of antenna element may exceed 90%. Besides, 4×4 antenna arrays of low mutual coupling for 60-GHz phased-array transceiver applications are also proposed. The mutual coupling of antenna elements is addressed by incorporating the via-bas...