This paper proposes a novel compact balanced-to-unbalanced bandpass filter. Firstly, a pre-design circuit is presented, which is composed of an inductive coupled-line bandpass filter and an out-of-phase capacitive coupled-line bandpass filter. A novel compact circuit with three coupled lines configuration, derived from the pre-design circuit, is then proposed for miniaturizing the balanced-to-unbalanced bandpass filter. A 2.4-GHz multilayer ceramic chip type balanced-to-unbalanced bandpass filter with a size of 2.0 mm x 1.2 mm x 0.7 mm is developed to validate the feasibility of the proposed structure. The filter is designed by using circuit simulation, as well as full-wave electromagnetic simulation softwares, and fabricated by the use of low-temperature co-fired ceramic technology. The measured results agree quite well with the simulated. According to the measurement results, the maximum insertion loss is 1.65 dB, the maximum in-band phase imbalance is within 3 degrees, and the maximum in-band magnitude imbalance is less than 0.32 dB.
|Number of pages||7|
|Journal||IEEE Transactions on Microwave Theory and Techniques|
|State||Published - Jul 2008|
- SERIAL CONFIGURATION
- TRANSMISSION ZEROS
Chen, K-T., & Chung, S-J. (2008). A novel compact balanced-to-unbalanced low-temperature co-fired ceramic bandpass filter with three coupled lines. IEEE Transactions on Microwave Theory and Techniques, 56(7), 1714-1720. https://doi.org/10.1109/TMTT.2008.926196