Abstract
A new high-order wideband planar balun filter is proposed in this paper. The balun filter is exact synthesized based on S-domain bandpass prototype using Richards' Theorem to fit the user-defined specifications. By analyzing the redundant element in the equivalent circuit, the output impedance of the balun filter can be arbitrarily assigned. To use an S-plane bandpass prototype other than a high-pass prototype can shrink the circuit area and improve the stopband performance. The lumped capacitor approximation suppresses the spurious response in the stopband and further reduces the circuit size. A high-order balun filter with a bandwidth of 100% and a reflection coefficient of -15 dB is implemented by combining of microstrip lines, slotlines, and coplanar striplines. The simulation and measurement results match well.
Original language | English |
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Article number | 6193187 |
Pages (from-to) | 2124-2130 |
Number of pages | 7 |
Journal | IEEE Transactions on Microwave Theory and Techniques |
Volume | 60 |
Issue number | 7 |
DOIs | |
State | Published - 8 May 2012 |
Keywords
- Balun filter
- bandpass prototype
- impedance transformation
- planar structure
- synthesis