新型埋藏式共平面波導之特性與其應用

Abstract

在此論文中提出了一個新型的埋藏式共平面波導，透過微機電的技術，此新型共平面波導的訊號線和地線可部分被彎曲並埋藏在基板中的溝槽中。由於在溝槽中的金屬線互相重疊的部分有很強的耦合電場，埋藏式共平面波導可以達到很低的特徵值阻抗(17.9歐姆)；此外，溝槽中的金屬可透過不同的製程係數去改變深度，因此埋藏式共平面波導可以在很小的面積下達到很大範圍的特徵值阻抗 (17.9-92.3歐姆)。由於新型埋藏式共平面波導中電場輻射到基板的量很小，因此它的介電質損耗可以有效的被抑制。跟傳統的共平面波導相比，埋藏式共平面波導可以大量的減低損耗，特別是在低特徵值阻抗的部分。製作在高阻值矽基板上的新型埋藏式共平面波導，在50 GHz時可以達到最低的損耗0.81 dB每公分。埋藏式共平面波導使用Schwarz–Christoffel 的保角變換技術去作分析；以quasi-TEM為假設的傳輸線模型參數：電阻、電感、電導和電容也被萃取出來並加以分析◦ 此外，電埋藏式共平面波導在射頻system-on-package的應用上可以做很好的結合，這些特性使微機電埋藏式共平面波導在RFIC應用上成為一個相當有前瞻性的傳輸線。

A new robust micromachined embedded coplanar waveguide is proposed in the thesis. The central and ground plates are partially bended and overlapped within the trench. Due to tight coupling of the E-field between the overlapped plates, the micromachined embedded CPW line is capable of wide range characteristic impedance (17.9-92.3 Ω) with compact size. Furthermore, the area in which E-field radiates into the substrate of the micromachined embedded CPW is quite small compared to the conventional CPW, and therefore the dielectric loss of the micromachined embedded CPW can be effectively suppressed. Compared with the conventional CPW lines, the embedded CPW lines have shown a great reduction on loss, especially in low-impedance range. The micromachined embedded CPW lines on the high-resistivity silicon substrate (ρs = 15000 Ω-cm) achieve a measured loss as low as 0.81 dB/cm at 50 GHz. The Schwarz–Christoffel mapping technique is utilized to analysis the ECPW. The quasi-TEM transmission line parameters, resistance, inductance, conductance, and capacitance (RLGC), were also extracted and analyzed. Moreover, the micromachined embedded CPW line can fit well in the RF system-on-package applications. These features make micromachined embedded CPW a promising transmission line for RFICs application.