Figs. 9 and 10 show photographs of the proposed amplifier and the setup for measurement, respectively. The circuit is built on the UL2000 substrate with a thickness of 0.762 mm, relative dielectric constant of 2.45, and loss tangent of 0.0025.
Each finite line has an electrical length of λ/4 at a normalizing frequency of 15 GHz.
The physical lengths of two two-section open stubs Z′2(1), Z′1(1), Z′2(2), and Z′1(2) are λ/8 at the normalizing frequency of 15GHz; those of two two-section stubs Z′2(3), Z′1(3), Z′2(4), and Z′1(4) are λ/2 at the normalizing frequency of 15GHz.
Fig. 9 Photograph of proposed amplifier
Fig. 10 Photograph of experiment setup.
Two bias tees are used to supply DC voltage to the circuit. The bias voltage is 4 V, and the bias current is 30 mA. Four chip capacitors are employed as DC blocks
RF in
Bias Tee
V
DS= 4 V
V
GS= -0.5 V
RF out
between the short stubs and ground at the input matching circuit. Four chip capacitors are employed as DC blocks between the short stubs and ground at the input matching circuit. Figs. 11–14 show the experimental results and RF simulation of S21, S12, S11, and S22, respectively. The measured S21 has a flat gain response for frequencies from 3.1 GHz to 10.6 GHz. In particular, S21 has a good fall-off rate in the stopband.
Fig. 11 S21 responses of proposed amplifier in microwave simulation and experimental result
Fig. 13 S11 responses of proposed amplifier in microwave simulation and experimental result
Fig. 14 S22 responses of proposed amplifier in microwave simulation and experimental result
The system group delay and stability factor (μ) are shown in Fig. 15 and Fig. 16, respectively. The proposed amplifier is unconditionally stable over the entire frequency band of interest and has flat group delay. This amplifier could be used as a UWB amplifier in a transmitter.
Fig. 15 Group delay of proposed amplifier
Fig. 16 Stability factor μ of proposed amplifier
The Pin-Pout relation and intermodulation distortion IMD3 are shown in Fig.17.
Its power conversion efficiency is shown in Fig.18. The third-order power interception point IP3 of this amplifier is about 24dBm at 4GHz, 5GHz and 6GHz.
Fig. 17 Output Power and IMD3 of proposed amplifier
Fig. 18 Output power and efficiency of proposed amplifier 5. Conclusion
A discrete-time domain method was proposed to design an ultra-wideband amplifier embedded with a band-pass filter. The proposed amplifier achieves a flat gain response. Four pairs of complex conjugate roots of the fifth-order ultra-wideband Chebyshev band-pass filter in the z-domain are implemented with four two-section open stubs that give transmission zeros in the lower and upper stopbands. Therefore, it has good fall-off selectivity. In addition, the unattainable characteristic impedances of transmission-line sections at the output matching network are modified by the frequency-bandwidth-impedance method. The novel method provides a basis for the integration of microwave applications and discrete-time signal processes.
References
[1] H. Harada and R. Prasad, Simulation and Software Radio for Mobile Communications, Artech House, Norwood, MA, 2002.
[2] D.-C. Chang and C.-W. Hsue, “Design and implementation of filters using transfer functions in the Z domain,” IEEE Trans. Microwave Theory Tech., vol.49, no.5, pp.979-985, May 2001.
[3] D.-C. Chang and C.-W. Hsue, “Wide-band equal-ripple filters in nonuniform transmission lines,” IEEE Trans. Microwave Theory Tech., vol.50, no.4, pp.1114-1119, April 2002.
[4] K. Nagatomo, Y. Daido, M. Shimizu, and N. Okubo, “GaAs MESFET characterization using least squares approximation by rational functions,” IEEE Trans.
Microwave Theory Tech., vol. 41, no.2, pp.199-205, February 1993.
[5] Fujitsu Microelectronics, Ltd. The data sheet of FSX017LG, Edition 1.2, July 1999.
[6] L.-C. Tsai and C.-W. Hsue, “Dual-band bandpass filters using equal-length, coupled-serial-shunted lines and Z-transform technique,” IEEE Trans. Microwave Theory Tech., vol.52, no.4, pp.1111-1117, April 2004.
[7] M. L. Edwards and J. H. Sinsky, “A new criterion for linear 2-Port stability using a single geometrically derived parameter,” IEEE Trans. Microwave Theory Tech., vol.40, no.12, pp.2303-2311, December 1992.
[8] Y. Chung, S. Cai, W. Lee, Y. Lin, C. P. Wen, K. L. Wang, and T. Itoh, “High power wideband AIGaN/GaN HEMT feedback amplifier module with drain and feedback loop inductances,” Electronics Letters, vol.37, no.19, pp.1199-1200, September 2001.
[9] D. Hanselman and B. Littlefield, Mastering MATLAB 5, Prentice Hall, Englewood Cliffs, NJ, 1998.
[10] E. C. Levi, “Complex-curve fitting,” IRE Trans. Automatic Control, vol.AC-4, pp.37-44, 1959.
[11] A. V. Oppenheim, R. W. Schafer, and J. R. Buck, Discrete-time Signal Processing.
Chapter Six, Second Edition, Prentice Hall, Englewood Cliffs, NJ, 1999.
[12] C.-W. Hsue, C.-W. Ling, and W.-T. Hung, “Discrete-time notch filter and its application to microwave filter,” Microwave and Optical Tech. Lett., Vl. 50, vol.6, pp.1596-1600, 2008.
國科會補助計畫衍生研發成果推廣資料表
日期:2011/12/02
國科會補助計畫
計畫名稱: 利用Z-轉換技術設計及製作嵌入微波濾波器之微波放大器 計畫主持人: 徐敬文
計畫編號: 97-2221-E-011-023-MY3 學門領域: 電磁
無研發成果推廣資料
97 年度專題研究計畫研究成果彙整表
計畫主持人：徐敬文 計畫編號：97-2221-E-011-023-MY3 計畫名稱：利用 Z-轉換技術設計及製作嵌入微波濾波器之微波放大器 IEEE Microwave and Wireless
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主 持 人 因 發 展 微 波 discrete-time domain technique 膺 選 為 2010 IEEE Fellow.
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本計畫利用 z-domain 技術完成 UWB ( 3.1GHz-10.6GHz ) 寬帶微波放大器，為國內通訊 產業發展 UWB 通訊系統磸定基礎。利益用 z-domain 技術設計微波放大器，具創新性，亦 為一般微波放大器設計，提供電路基本架構，具學術與實務價值。未來將利用此技術發展 LTE 基地站用 40 watts 射頻功率放大器。