Reconfigurable bandpassfilter with a three-to-one switchable passband width

A reconfigurable bandpass filter is described that aims to preserve the optimal performance of a broad-band system under changing signal conditions. It does so by allowing the passband width of the system's receiver to adapt. The filter can be switched between two discrete states with widely differing bandwidths of 500 and 1500 MHz, respectively, while keeping the passband responses centered at 10 GHz. The physical implementation comprises a hybrid-integrated microstrip circuit on a 0.010-in-thick quartz substrate. The circuit employs commercial beam-lead p-i-n diodes to switch fixed-valued reactance elements. Despite the presence of semiconductor switching devices, the filter. behaves very linearly, exhibiting measured passband third-order output-referenced intercept points that exceed 46 dBm in both switched states.