Читать книгу Antenna-in-Package Technology and Applications - Duixian Liu - Страница 18

In 1998, Zhang started to work in the Division of Circuits and Systems at the School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore. The division soon initiated a strategic research project entitled “Software radio on a chip.” Zhang was tasked to develop an antenna technology for the project. Inspired by the structural similarity shared by a microstrip antenna and a microchip, shown in Figure 1.3, and foreseeing the outcome of an interesting antenna solution, Zhang immediately started to investigate the antenna performance of the microchip. First, Zhang did antenna experiments with used microchips, as shown in Figure 1.4a. Then, Zhang tried PCB mock‐ups, as shown in Figure 1.4b. Encouraged by good antenna results from the microchips and PCB mock‐ups, the research team led by Zhang realized more sophisticated designs, as shown in Figure 1.4c,d, with low‐temperature co‐fired ceramic (LTCC) technologies in 2004 [12]. It is interesting to note that differential microstrip patch and meander antennas were designed to suit high‐level integration of wireless SoCs. They were integrated on the top surfaces of two ball grid array (BGA) packages. Both packages had cavities to house wireless SoC dies. The interconnects from the die to the antenna were cascaded bond wires, traces, and vias. The interconnected die was encapsulated with epoxy.

Figure 1.3 Photograph of a microchip.

In 2000, Song et al. at University of Birmingham presented an integrated antenna package [13]. An electrically small feed antenna was designed on a semiconductor substrate, which also supported the RF front‐end circuits. The parasitic radiator placed above the feed antenna also acted as a top cover, sealing the entire package. Later, Song et al. presented another integrated antenna package [14]. A small antenna was embedded within the chip encapsulating material. A parasitic radiator was placed in close proximity to the embedded antenna, where it enhanced the poor gain and bandwidth of the packaged antenna.

In 2001, package engineers started to tackle the same problem. Lim et al. at the Georgia Institute of Technology managed to integrate RF passives, a patch antenna, and chips at the package level to enhance the overall performance of and to add more functionalities to an SoP paradigm [15]. Mathews et al. disclosed a package with an integral shield and antenna for a complete Bluetooth radio design [16].

In 2003, Ryckaert et al. at the Interuniversity Microelectronics Center, Belgium reported the co‐design of circular‐polarized slotted patch antenna with a wireless local area network (WLAN) transceiver in a multilayer package [17]. Popov et al. at the Institute of Microelectronics, Singapore reported the design of part of an RF chip package as a dielectric resonator antenna with a high dielectric constant when the antenna feed was integrated with the rest of the circuitry [18]. Leung at City University of Hong Kong independently proposed adding the chip package function to a dielectric resonator antenna in 2004 [19].

In 2005, Castany et al. at Fractus, Spain filed a patent about the integration of fractal antennas in a chip package [20]. They claimed that fractal antennas could provide very good antenna performance while allowing a high degree of miniaturization and an enhancement of isolation between the antenna and the die in the package.

Figure 1.4 Photographs showing the evolution of the integration of antenna in package: (a) an antenna on a used microchip package, (b) an antenna on a chip package mock‐up, (c) a microstrip patch antenna as an LTCC package, and (d) a microstrip meander antenna as an LTCC package.

In 2006, Brzezina et al. at Carleton University reported planar antennas with transceiver integration capability for ultra‐wideband (UWB) radios [21]. Sun et al. devised a novel technique that reduces the size of a conventional planar antenna by 40% and used it as a package to house a single‐chip UWB radio [22].

In 2007, Wi et al. at Yonsei University, Korea presented an antenna‐integrated package [23]. A modified U‐shaped slot antenna was designed and measured, showing bandwidth of 180 MHz at 5.8 GHz. A parametric study was conducted with a full‐wave electromagnetic solver to determine the critical factors in design and fabrication, as well as to estimate the performance accuracy of the antenna‐integrated package.