Design of Sext-Band Bandpass Filter and Sextaplexer Using Semilumped Resonators for System in a Package

In this paper, using semilumped resonators, one sext-band bandpass filter and one sextaplexer are proposed. The two circuits are fabricated using microstrip technology, and the semilumped resonator consists of two identical microstrip lines and a chip inductor at the center. In comparison with conventional half-wavelength uniform resonator, the semilumped resonator is compact and has better control over harmonic frequencies. In addition, the two circuits utilize a distributed coupling technique to integrate bandpass channel filters. This technique has a low loading effect resulting in a high design freedom that is essential for multiband circuits.