A compact elliptic‐function‐response bandpass filter using slotline resonators and stubs is designed in this letter. This slotline resonator is composed by one loop resonator with four corner‐patch perturbation and stubs. The nature of coupling between the degenerate modes is investigated with respect to the perturbation size. Also, slotline stubs are applied to miniature the filter's size by keeping excellent performance. Results verify that the central frequency and the fractional bandwidth of the proposed filter are 5.23 GHz and 7.45%, respectively. A good agreement between simulation and measurement verifies the validity of this design methodology. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:641–644, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26603

reported VCO articles [6][7][8][9][10], allows to conclude that the circuit presented achieves the widest tuning range, covering the range from 5.97 GHz to 7.3 GHz corresponding to 20.1% and the best FOM of À183.6 while attaining comparable performance in phase noise, power consumption and chip area. CONCLUSIONSA wider tuning range of 1.5V CMOS transformer-based LC VCO was proposed and successfully implemented in the 0.18 lm 1P6M CMOS technology. The LC tank using a decoupling transformer with two tunable varactors greatly extends the tuning range from 5.97 GHz to 7.3 GHz and achieves good performances in what concerns low supply voltage of 1.5 V, low phase noise of À110.9 dBc/Hz at 1 MHz offset, small chip area of 0.69 Â 0.696 mm 2 , low power consumption of 9.51 mW and a better FOM of À183.6 dB. ACKNOWLEDGMENTSThe authors would like to acknowledge Professor Ron-Yi Liu for layout guidance and the fabrication support and chip fabrication provided by National Chip Implementation Center (CIC). A quadrature CMOS VCO using transformer coupling and current reuse topology, IEICE Trans Commun E90-B (2008), 346-348. 4. H.H. Hsieh and L.H. Lu, A high-performance CMOS voltage-controlled oscillator for ultra-low-voltage operations, IEEE Trans Microwave Theory Tech 55 (2007), 467-473. 5.

In this letter, a compact dual‐band microstrip bandpass filter (BPF) with independently controlled center frequencies is designed using meander short‐circuit quarter‐wavelength resonators. Its coupling scheme and equivalent circuit model are analyzed. A good agreement between simulation and measurement verifies the validity of this design methodology. The overall size for the proposed BPF is about 0.17λg × 0.17 λg. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:344–346, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26590

A compact multi-mode bandpass filter with high selectivity and a wide stopband is proposed in this article. The quintuple-mode resonator is proposed by introducing a triple-mode resonator into a dual-mode resonator. Due to the intrinsic characteristic of the proposed resonator, two transmission zeros are created at both sides of the passband for enhancing selectivity. Furthermore, two transmission zeros are generated by the input and output feed lines, leading to sharp skirts and a wide stopband. The simulated responses show a 3-dB fractional bandwidth of 25.8% at the central frequency (2.4 GHz). Measurement results agree well with the simulated results.