LTCC Out-of-Phase Filtering Power Divider Based on Multiple Broadside Coupled Lines

This paper presents a compact microwave out-of-phase filtering power divider in low-temperature co-fired ceramic (LTCC) technology. The proposed device is composed of three resonators and an isolation resistor. One resonator is symmetrically coupled with the other two by employing multiple broadside coupled lines. Utilizing the transmission line theory, the magnitude and phase characteristics are addressed. Theoretical analysis indicates the proposed circuit provides two signal paths with bandpass responses and 180 degrees phase difference. Also, the realization of the isolation between two output ports is analyzed. For validation, a filtering power divider with out-of-phase outputs is designed, fabricated, and measured. It occupies a compact area of 3.1 x 3.2 x 1.6 mm(3). Comparisons of the measured and simulated results are presented to verify the theoretical method.