IPD broadband balun design for GSM applications

This paper presents the integrated passive device (IPD) broadband balun design by second-order lattice type topology for GSM applications. Analytical expressions of inductance and capacitance values are derived from ABCD matrix with easy making lump element values evaluated accurately. Finally, the two broadband baluns are designed based on silicon substrate for the theory's demonstration which exhibit the amplitude difference lower than 0.8 dB, insertion loss better than -0.8 dB and phase delay difference located at 180 +/- 4 degrees from the frequency of 0.8 GHz ~ 1 GHz and 1.5 ~ 2.1 GHz covering all GSM low/high band.