Varactor-based frequency-tuned microwave quarter-wavelength side-coupled ring resonator

A center-frequency-tuned microwave quarter-wavelength side-coupled ring resonator based on the varactor diodes is presented. Four identical varactor-based tuning circuits are applied at every entry point of the coupled-lines in the ring resonator to give capacitance effects and cause an increment of electrical length and thus results in tuned center frequency at the desired frequency band. The complete tunable resonator circuit is simulated using EM circuit simulator. The proposed filter is then realized and fabricated on FR4 substrate.

[1]  J.I. Alonso,et al.  Tunable combline filter with continuous control of center frequency and bandwidth , 2005, IEEE Transactions on Microwave Theory and Techniques.

[2]  M.B. Steer,et al.  A reconfigurable bandpass filter for RF/microwave multifunctional systems , 2005, IEEE Transactions on Microwave Theory and Techniques.

[3]  J. Huangfu,et al.  A Tunable Microstrip Bandpass Filter With Two Independently Adjustable Transmission Zeros , 2011, IEEE Microwave and Wireless Components Letters.

[4]  M. Miao,et al.  A 10–14 GHz RF MEMS tunable bandpass filter , 2008, 2008 9th International Conference on Solid-State and Integrated-Circuit Technology.

[5]  M. Salleh,et al.  Synthesis of tuneable ring-based bandpass filter , 2008, 2008 Asia-Pacific Microwave Conference.

[6]  Gabriel M. Rebeiz,et al.  A Two-Pole Two-Zero Tunable Filter With Improved Linearity , 2009, IEEE Transactions on Microwave Theory and Techniques.

[7]  I. Hunter,et al.  Electronically Tunable Microwave Bandpass Filters , 1982 .

[8]  Gabriel M. Rebeiz,et al.  Corrugated Microstrip Coupled Lines for Constant Absolute Bandwidth Tunable Filters , 2010, IEEE Transactions on Microwave Theory and Techniques.

[9]  M. K. Mohd Salleh,et al.  Quarter-Wavelength Side-Coupled Ring Resonator for Bandpass Filters , 2008, IEEE Transactions on Microwave Theory and Techniques.

[10]  Gabriel M. Rebeiz,et al.  A varactor-tuned RF filter , 2000 .

[11]  Sang-Won Yun,et al.  Hairpin Tunable Bandpass Filter with Improved Selectivity and Tunability , 2007, 2007 Asia-Pacific Microwave Conference.

[12]  Jia-Sheng Hong,et al.  An Electronically Tuned Bandstop Filter Using BST Varactors , 2008, 2008 38th European Microwave Conference.

[13]  Gabriel M. Rebeiz,et al.  Low-Loss 5.15–5.70-GHz RF MEMS Switchable Filter for Wireless LAN Applications , 2006, IEEE Transactions on Microwave Theory and Techniques.