寬頻毫米波開關設計

Abstract

本論文提出兩個架構不同的寬頻毫米波開關，此兩電路晶片皆使用Win 0.15μm pseudomorphic high electron mobility transistor MMIC process 製成實現。 第一個是60GHz單刀雙擲毫米波開關，此開關設計是利用兩級並聯電晶體以提升高頻下的隔離度，並且以改良的電晶體布局降低電晶體與訊號線間的寄生效應與使用並聯三個接地孔(via-hole)降低接地孔在高頻下的電感性的方式提升電路可操作的頻寬。電路模擬的結果顯示在40GHz到70GHz之間，其輸入損耗皆小於3dB，且擁有良好的隔離度(>32dB)。 第二個是行進波單刀雙擲開關，此開關設計應用行進波之概念，其開關導通模式是以電晶體在關閉模式下的等效電容配合小段傳輸線的等效電感，合成出人工傳輸線以達到寬頻低損耗之效果，其關閉模式則是利用電晶體導通時的等效小電阻以達到極小的輸入阻抗將訊號反射以達到良好的隔離度。其模擬結果顯示在30GHz到123GHz之間，其輸入損耗皆小於5dB，且擁有良好的隔離度(>20dB)。

This thesis presents two millimeter-wave circuits. Both of the proposed circuits are fabricated by Win 0.15μm InGaAs pseudomorphic high electron mobility transistor (pHEMT) MMIC process. First, we present a 60GHz SPDT T/R switch in shunt configuration and reduce the parasitic components by FET-integrated line structure and connecting three via-holes in parallel. The SPDT switch shows low insertion loss less than 3 dB and isolation greater than 32 dB from 40 to 70 GHz. The highest isolation is achieved at 60 GHz with a low insertion loss of 2.05 dB. Second, we present a broad band millimeter-wave SPDT switch by utilizing the traveling-wave concept. The traveling-wave uses the small signal models of off-state pHEMTs and short transmission lines to form an artificial transmission line that has a low insertion loss over a broad frequency range. The SPDT switch has low insertion loss less than 5 dB and isolation greater than 20 dB from 30 to 123 GHz.