A Two-Pole Lumped-Element Programmable Filter With MEMS Pseudodigital Capacitor Banks

This paper presents a novel two-pole reconfigurable bandpass filter on alumina substrate for applications in X- and S-bands. An analytical approach was followed for synthesis of multiple filtering characteristics. A microstrip network on alumina was then optimized to implement a set of switched filtering functions. Finally a reconfigurable filter was fabricated and tested in order to validate the proposed approach. This filter exploits five 3-bit capacitor banks controlled with microelectromechanical systems ohmic switches to achieve 12 states with 37.5% tuning range between 1.51-2.26 GHz. Several tuning mechanisms are demonstrated including frequency, bandwidth tuning, and frequency + bandwidth tuning. Good agreement with theoretical results has been obtained.