On-chip Antennas with Silicon Lens and with AMC structure for Millimeter Wave
Date Issued
2016
Date
2016
Author(s)
Chen, Wei-Kai
Abstract
In this thesis, two kinds of on-chip antennas which operating at millimeter wave bands are proposed, namely, a slot ring antenna at 140 GHz using CMOS 40 nm technology and a bow-tie antenna at 38 GHz using CMOS 90 nm technology. First of all, a 140 GHz slot ring on-chip antenna is designed and fabricated. To comply with design rules of standard CMOS process, slot antenna is selected due to its easy adjustment of metal density. In addition, low-loss silicon bullet-shaped lens are mounted below the chip to convert the power of surface wave to radiation, thereby increasing antenna gain and efficiency. Three different sizes of lens are studied in full-wave simulation to find out optimized lens shape. Moreover, since in practice, it is hard to mount chip exactly at the center of the lens, the influences of the chip position on the offset of main beam is considered. This antenna features high gain and narrow beam. Afterward, in order to measure the reflection coefficient by probe, they are mounted on lossy silicon wafers to emulate the effects of silicon lens. Due to equipment limitation, measured frequency is from 140 to 220 GHz. The 10-dB bandwidth of this antenna is from at least 140 to 176 GHz. As for the antenna patterns, for silicon lens with radius 2.5, 5 and 8 mm, the simulated antenna gains are 11.3, 17.3 and 21.3 dB, respectively. The antenna efficiency is about 37% for all cases. Next, a 38 GHz bow-tie on-chip antenna with artificial magnetic conductor (AMC) is studied and fabricated. Broadband bow-tie antenna is chosen and AMC is designed below to enhance efficiency. Differential-mode feeding is adopted to work with active on-chip circuit. Since double-layer square AMC has small unit cell compared with other structures, it is used to put more cells in a finite area. The total size of this chip is 2.1 1.5 mm2. Its 10-dB bandwidth is from 34.4 to 42.1 GHz. Due to the unexpected surrounding metal from dicing, the simulated antenna gain drops from –3.2 to –5.1 dB while the efficiency reduces from 11 to 7 %. These two antennas are all integrated with active circuits on chips. Between the antennas and the active circuits, bond pads are added in order to measure each antenna and active circuit respectively. In addition, measurement setups for both chips are proposed to check not only antenna patterns but also the complete chip properties.
Subjects
millimeter wave
on-chip antenna
integrated silicon lens
slot ring antenna
bow-tie antenna
artificial magnetic conductor
Type
thesis
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