在本論文中，我們提出了兩種應用於Ka頻段，不同架構之次諧波降頻混頻器。並透過國家晶片中心(CIC)，利用WIN 0.15UM PHEMT製程以單石微波積體電路來實現。

在第一種架構之次諧波混頻器中，我們利用反並聯式配對二極體對基頻混頻訊號的抑制特性，來做為次諧波混頻器之基本組件。將四對反並聯式配對二極體接成環狀結構，並藉由兩組藍格偶合器將射頻及本地震盪源訊號功率等分成相差90度之訊號，饋入環狀結構。如此之架構，在射頻頻率由26至38 GHz的頻段內皆有良好之射頻及本地震盪源對中頻隔離度，其隔離度分別大於25及19 dB。而其轉頻損耗也都小於17 dB (此為實際量測結果)，在34至38 GHz間轉頻損耗甚至可小於15 dB，為一寬頻之次諧波混頻器。

在第二種架構中，我們則是利用FET來實現主動式次諧波混頻器。此為串疊結構之次諧波混頻器，在轉頻損耗及消耗功率的取捨下，我們選擇消耗功率為21.2毫瓦，射頻頻率由28.5至30.4 GHz的頻段內其轉頻損耗皆小於6 dB，射頻及本地震盪源對中頻隔離度分別為大於42及12 dB (此為模擬結果)，為一較為窄頻之次諧波混頻器。

比較此二不同架構之次諧波混頻器，可知被動式(二極體)之次諧波混頻器可以得到較大的頻寬，而主動式次諧波混頻器則可達到較佳之轉頻損耗。無論是主動式或被動式皆有其優缺點，其選擇則視所應用之需求而定。

We have proposed two novel structures of sub-harmonic down-conversion mixers for Ka band application in this thesis. Through National Chip Implementation Center (CIC), the circuits are implemented in form of monolithic microwave integrated circuit (MMIC) by the WIN 0.15UM PHEMT process.

In the first mixer structure, we take the advantage of the fundamental mixing suppression of the anti-parallel diode pair (APDP), and use it as the basic unit in the proposed sub-harmonic mixer. Four pairs of anti-parallel diodes are connected in a ring form. Both the RF and LO signals are divided to two half power signals with 90o phase difference by Lange couplers, and fed to the ring structure. The measured result shows that this structure has good RF/LO to IF isolations. The RF/LO to IF isolations are more than 25 and 19 dB from 26 to 38 GHz. The conversion loss is less than 17 dB in the same range. (In the range from 34 to 38 GHz, the conversion loss is less than 15 dB.) It is a broad band mixer.

The FETs are applied to implement the active sub-harmonic mixer, in the second structure. Two FETs are connected in a cascode topology. It is a trade off between the conversion loss and power consumption. The power consumption is chosen to be 21.2 mW, and the conversion loss is less than 6 dB from 28.5 to 30.4 GHz in simulation. The RF/LO to IF isolations are more than 42 and 12 dB. It is a narrow band mixer.

Comparing these two sub-harmonic mixers, we can get that the passive (diode) sub-harmonic mixer is broader band, while the conversion loss is better in the active sub-harmonic mixer. The choice between the passive and active sub-harmonic mixers depends on the applied requirement.

[1] M. C. Comparini, M. Feudale, and A. Suriani, “Applications of HEMT devices in space communication systems and equipment: a European perspective”, Solid-State Electronics, VOL. 43, p.1577-p.1589, 1999.
[2] B. Matinpour, N. Lal, J. Laskar, R. E. Leoni, and C. S. Whelan, ”K-band receiver front-ends in a GaAs metamorphic HEMT process”, IEEE Transactions on Microwave Theory and Techniques, VOL. 49, NO. 12, p.2459–p.2463, December 2001.
[3] I. D. Robertson and S. Lucyszyn, “RFIC and MMIC design and technology”, Institution of Electrical Engineers, 2001.
[4] K. Kawakami, M. Shimozawa, H. Ikematsu, K. Itoh, Y. Isota and O. Ishida, “A millimeter-wave broadband monolithic even harmonic image rejection mixer.”, 1998 IEEE MTT-S Digest, p.1443-p.1446, 1998.
[5] W. C. Chen, S. Y. Chen, J. H. Tsai, T. W. Huang, and H. Wang, ”A 38-48-GHz miniature MMIC subharmonic mixer”, Gallium Arsenide and Other Semiconductor Application Symposium, 2005. EGAAS 2005. European, p.437– p.440, 2005.
[6] M. Kim, J. B. Hacker, E. A. Sovero, D. S. Deakin, and J. H. Hong, “A millimeter-wave multifunction HEMT mixer”, IEEE Microwave and Guided Wave Letters, VOL. 9, NO. 4, p.154-p.156, April 1999.
[7] “RF, RFIC & Microwave Theory, Design”, www.rfic.co.uk
[8] F. Giannini, and G. Leuzzi, “Nonlinesar Microwave Circuit Design”, Wiley, 2004.
[9] 鄔文杰,“關鍵性砷化鎵單石微波積體電路”, 國立台灣大學電機工程學研究所博士論文, 2003.
[10] 魏淑芬,“毫米波接收端單晶積體電路之研製”, 國立臺灣大學電信工程學研 究所碩士論文, 2001.
[11] P. Blount, and C. Trantanella, “A high IP3, subharmonically pumped mixer for LMDS applications”, 2000 IEEE GaAs Digest, p.171–p.174, 2000.
[12] D. An, S. C. Kim, W. S. Sui, H. J. Han, H. S. Lee, W. Y. Uhm, H. M. Park, S. D. Kim, D. H. Shin, and J. K. Rhee, “High conversion gain V-band quadruple subharmonic mixer using cascode structure”, 2003 IEEE MTT-S Digest, p.911-p.914, 2003.
[13] Stephen A. Maas, “Microwave mixers”, Artech House, 1993.
[14] K. Itoh, A. Iida, Y. Sasaki, and S. Urasaki, “A 40GHz band monolithic even harmonic mixer with an antiparallel pair”, 1991 IEEE MTT-S Digest, p.879-p.882, 1991.
[15] M. Cohn, J. E. Degenford, and B. A. Newman, “Harmonic mixing with an antiparallel diode pair” IEEE Transactionson Microwave Theory and Techniques, VOL. 23, NO. 8, p.667-p.673, August 1975.
[16] J. J. Hung, T. M. Hancock, and G. M. Rebeiz, “A 77 GHz SiGe sub-harmonic balanced mixer”, IEEE Journal of Solid-State Circuits, VOL. 40, NO. 11, p.2167-p.2173, November 2005.
[17] J. Kim, and J. Choi, “Design of a resistive cascode fet direct-conversion mixer with zero bias-current”, Microwave and Optical Technology Letters, Vol. 42, No. 6, p.516-p.518, September 20 2004.
[18] J. Kim, and J. Choi, “Design of a subharmonic cascode FET mixer for an IMT-2000 base station”, Microwave and Optical Technology Letters, Vol. 39, No. 6, p.515-p.518, December 20 2003.
[19] A. Orzati, F. Robin, H. Meier, H. Benedikter, and W. Bächtold, “A V-band up-converting InP HEMT active mixer with low LO-power requirements”, IEEE Microwave and Wireless Components Letters, VOL. 13, NO. 6, p.202-p.204, June 2003.
[20] Y. L. Kok, M. Ahmadi, H. Wang, B.R. Allen, and T. Lin. "A Ka-band monolithic single-chip transceiver using sub-harmonic mixer" 1998 IEEE Radio Frequency Integrated Circuits (RFIC) Symposium, p.235-p.237, 1998.
[21] W. Ko and Y. Kwon, “A GaAs-based 3–40 GHz distributed mixer with cascode FET cells” 2004 IEEE Radio Frequency Integrated Circuits (RFIC) Symposium, p.413–p.416, 2004.
[22] I. Kallfass, T. Purtova, A. Brokmeier,W. Ludwig, and H. Schumacher, “One single traveling-wave MMIC for highly linear broadband mixer and variable gain amplifiers”, 2005 IEEE MTT-S Digest, p.97–p.100, June. 2005.