適用於WPAN通訊系統之晶片型主動天線設計

Abstract

IC整合電路，是現今CMOS製程中，極大的一個趨勢。本次為期兩年的計畫之中， 我們提出了應用在60GHz (Wireless Personal Area Network, WPAN)系統的晶片天線以及 主動天線之應用。在此分述如下： 一. 晶片天線：在歐美各國的頻率使用的規格，WPAN的頻帶之中，約有8GHz的頻帶 可以使用，可提供高於1Gbps之資料傳輸。而此頻帶應用於無線網路主要有下列特 色：(1)毫米波頻段的頻寬較寬，在同樣的頻寬之下，可以用更高速的速率進行資料 傳輸。(2)由於是毫米波，因此波長相對很短，因此天線所需要的尺寸較小。(3)由於 大氣的高衰減性，相當適合應用在短距傳輸，也降低多重路徑反射的問題。 二. 主動天線：由於60GHz頻帶在大氣中衰減得相當快，也因此，若是單只有天線，所 能接收到的信號必定相當微弱，有鑑於此，在完成第一年的計畫之後，以得到之成 果做為基礎，將單一晶片天線和電路直接做一個整合。由於共振型態天線可以視為 一個大電感，或是一個特定頻率的諧振腔，故可以用此特性，將天線架構，和振盪 器( Oscillator )或是混波器(Mixer)結合在一起。進而達到縮小整個電路的尺寸，也可 以避免掉因為要相互匹配到50Ω而需要額外的電路元件而造成功率的轉移損耗。 第一年研究計畫：以 0.18 及0.13μm CMOS 製程設計晶片天線 在CMOS製程當中，RF前端電路幾乎得已實現，唯獨天線仍無法有效的整合至IC積 體電路之中。為了能在IC得已實現的尺寸之下製作晶片天線，我們選定了60GHz頻帶， 在此頻帶中約有將近8GHz左右的頻寬是可以使用的(即WPAN系統)。而現今所能提出 來的晶片天線架構不外乎是下列幾種：單極天線[1.1]，平面倒F天線[1.3]，偶極天線 [1.9]，曲折天線[1.10]，迴圈天線[1.11]。在此，我們利用PIFA的特性，易於matching， 且頻寬較寬，並且我們是採用共平面波導的方式去饋入，接著設計天線主體的部分， 主要還是以單極天線為主體架構，然後在某些特定的地方做曲折的動作，來達到天線 尺寸縮小的目的。

IC integrated circuit is a trend of CMOS process nowadays. In this proposal by two years, we bring up an idea about an application for 60GHz (Wireless Personal Area Network, WPAN) chip antenna and active antenna. It is described as following: 1) Chip Antenna: The frequency allocations in America and Europe, which is about 8GHz bandwidth we can use in WPAN band that can supply higher than 1Gbps data transmission rate. The following descriptions are the characteristics of the band which is applied in wireless network. (1)The bandwidth is wider at millimeter-wave band. It can transport data in higher rate at the same bandwidth. (2) Because of the millimeter-wave, the wave length is very short and the need of the size of the antenna is smaller. (3) Because of the characteristics of the high decay of the atmosphere, this band is very appropriate for short range communication and reduces the multi-path reflection problems. 2) Active Antenna Because the 60GHz frequency band signal decays so fast in atmosphere, the signal we received must be very weak if we only have antenna structure. So, after the achievement of the first year proposal, we base on the result and integrate the chip antenna into the circuit. And we can see the resonance type antenna as an inductor or a resonator at the critical frequency. So we can use the characteristics and then integrated the antenna structure into oscillator or mixer. As a result, we can reduce the size of the antenna and decrease the power loss which is caused by the additional components for matching to 50 ohm. The First Year Proposal: The Design of Chip Antenna by Using 0.18 and 0.13 μm CMOS Process The RF front-end circuit can realize almost in CMOS process but only the antenna is not. In order to realize the chip antenna in practical size of IC, we choose the 60GHz frequency band. At this band, the bandwidth we can use is about 8GHz, which is the WPAN system. Nowadays, the proposed structure of the chip antenna can be classified such parts: monopole antenna [1.1], planer inverted F antenna (PIFA) [1.3], dipole antenna [1.9], meander antenna [1.10], loop antenna [1.11]. For these types antenna, we use the characteristics of the PIFA type which is easy to matching and has wider bandwidth. And we choose the coplanar waveguide (CPW) structure to feed the antenna. Next, the part of design of the antenna body, we base on the structure of the monopole antenna and then bend the antenna at the critical position to reduce the size of the antenna.