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論文研討: H.Issa #1,J.-M.Duchamp #2,S.Abou-Chahine *3,and Ph.Ferrari #4 “Compact Semi-Lumped Two-Pole DBR Filter with SpuriousSuppression” 報告人: 碩研電子一甲 MA130216 蘇暐倫 Abstract A compact second order DBR passband filter having a center frequency 1 GHz is designed, fabricated and measured. The miniaturization is achieved by capacitive loading of high impedance transmission lines. The obtained surface miniaturization percentage of the miniature filter with respect to a reference conventional one is of 95% (25 x 25 mm2). Measurement results show that by integrating miniature lowpass structures (for which the cutoff frequency is derived), the broadband response is spurious free until about eight times the center frequency. Index Terms — Bandpass filter, DBR, miniaturization. H. Issa #1, J.-M. Duchamp #2, S. Abou-Chahine *3, and Ph. Ferrari #4 “Compact Semi-Lumped Two-Pole DBR Filter with Spurious Suppression” MINIATURE DBR RESONATOR A classical DBR resonator is realized by associating two different parallel open-ended stubs [5]. Each stub brings its own transmission zero and the whole resonant structure behaves like a shunt-connected parallel resonant circuit in the vicinity of fr, the frequency at which the total length equals half wavelength. The miniaturization of the DBR resonator is achieved by using high characteristic impedance Zci stubs loaded at their ends by capacitors connected to the ground [4]. The use of high Zci permits higher miniaturization. MINIATURE TWO-POLE DBR FILTER A. Principle i- Classical DBR filter ii- Semi-miniature DBR filter Fig. 1. Equivalent electrical circuits of two-pole (a) classical DBR filter, and (b) semi-miniature DBR filter. iii- Miniature DBR filter with integrated low-pass structures structures Fig. 2. Schematic of (a) conventional quarter-wavelength inverter, (b) miniature impedance inverter, and (c) miniature two-pole DBR filter. Expression of the cut-off frequency fc B. Design i- Semi-miniature DBR filter Fig. 3 Simulated transmission (S21) and reflection (S11) coefficients for the two miniature DBR resonators. Fig. 4. Simulated transmission and reflection coefficients for the twopole semi-miniature DBR bandpass filter. TABLE I. DESIGN PARAMETERS VALUES OF THE TWO MINIATURE DBRS. ii- Miniature DBR filter TABLE II. DESIGN PARAMETERS VALUES OF STUBS AND IMPEDANCE INVERTERS OF THE SEMI-MINIATURE FILTER. Fig. 5. Simulated transmission and reflection coefficients of the optimized two-pole semi-miniature DBR bandpass filter. Fig. 6 Simulated transmission and reflection coefficients of the two-pole miniature DBR filters: broadband response (left) and passband (right). TABLE III. DESIGN PARAMETERS VALUES OF STUBS AND IMPEDANCE INVERTERS OF THE MINIATURE FILTER. FABRICATION AND MEASUREMENT Fig. 7. A photograph of the two-pole (a) classical, (b) semi-miniature, and (c) miniature DBR filters. Fig. 8. Measured passband response: (a) transmission and (b) reflection coefficients, and (c) broadband response of the miniature DBR filter. CONCLUSION A compact second order DBR filter at 1 GHz with secondary lobe suppression was presented. The miniaturization percentage is 95% with respect to a classical DBR filter. The broadband frequency response is spuriousfree up till 7.5 GHz. However, the insertion loss is higher than that of the classical filter (0.7 dB against 0.46 dB for the classical filter). About 0.4 dB of the losses are due only to the losses of the capacitors and the via holes. REFERENCES [1] T. Hirota, et al., “Reduced-Size Branch-Line and Rat-Race Hybrids for Uniplanar MMIC’s”, IEEE Trans. Microwave Theory Tech., vol. 38, no. 3, pp. 270-275, March 1990. [2] E. Pistono, et al., “Compact Fixed and Tune-All Bandpass Filters Based on Coupled Slow-Wave Resonators,” IEEE Trans. Microwave Theory Tech., vol. 54, no. 6, pp. 2790-2799, June 2006. [3] J. Drozd and W. Joines, “A Capacitively Loaded Half-Wavelength Tapped-Stub Resonator,” IEEE Trans. Microwave Theory Tech., vol. 45, no. 7, pp. 1100-1104, July 1997. [4] H. Issa et al., « Miniaturized DBR Filter: Formulation and Performances Improvement », IEEE MTT-S, 2008. [5] C. Quendo, et al., “Narrow Bandpass Filter Using Dual-Behavior Resonators”, IEEE Trans. MTT, vol. 51, n° 3, pp. 734-743, Mars 2003. [6] C. Quendo, et al., “Narrow bandpass filters using dual-behavior resonators based on stepped-impedance stubs and different-length stubs”, IEEE Trans. MTT, vol. 52, n° 3, pp. 1034-1044, Mars 2004. [7] A. Manchec, et al., “Synthesis of dual behavior resonator (DBR) filters with integrated low-pass structures for spurious responses suppression,” IEEE Microw. Comp. Lett., vol. 16, no. 1, pp. 4–6, Jan. 2006. [8] H.Issa #1,J.-M.Duchamp #2,S.Abou-Chahine *3,and Ph.Ferrari #4 “Compact Semi-Lumped Two-Pole DBR Filter with SpuriousSuppression”