NOVELL MICROMACHINED LUMPED ELEMENT BANDPASS FILTER WITH AN ADDITIONAL ZERO IN THE BANDSTOP, FOR WLAN 5200 APPLICATIONS
A. A. MULLER, D. NECULOIU, D. VASILACHE, A. CISMARU, P. PONS, R. PLANA, L. BARY, A. MULLER

Abstract. This paper describes the design and realization of a new lumped element bandpass filter starting from a second order capacitive coupled resonator topology. An additional series inductor is inserted in the filter classical topology for shifting 2 transmission zeros on the real frequency axes in the filter’s bandstop, to improve the high frequency response of the filter. Design equations for the new bandstop resonance frequency are presented together with the analysis of the correspondence between the bandpass and bandstop attenuation vs. the quality factor of the shunt and series inductors used. The filter is supported on a 6.4 µm thick membrane, with a relative dielectric permittivity of 5.4 in CPW technology, using silicon micromachining technologies. Measurements illustrated a minimum 2.75 dB insertion loss at 5.5 GHz in the bandpass, while achieving more than 40 dB attenuation at 8 GHz.
Index Terms: Bandpass, CPW, filter, inductors, lumped, micromachining, quality factor, transmission zero, WLAN.