Switchable bandpass filter for WiFi-UMTS reception standards

A reconfigurable bandpass filter able to switch between WiFi and UMTS reception standards is presented. The topology allows achievement of two accurate centre frequencies, each associated with a precisely defined bandwidth, using six pin diodes. The design carefully takes into account the external quality factor for both filter states to ensure a good impedance match at each band of operation. Coupling coefficients and resonator lengths produce the bandwidths and centre frequencies required by both standards definitions. Surface mount components were carefully modelled and included in simulations. Simulated and measured results show excellent agreement.