This invention relates to the field of resonators and filters and more specifically to switchable and tunable coplanar waveguide resonators and filters using micro-electro-mechanical switches.
A need exists for switchable and tunable filters for both wideband and multiband communication systems that are small in size, inexpensive and easy to manufacture. Prior art switchable/tunable filters use resonant ring arrangements with diodes used as switches to select filter response. These diode switches tend to be large in size and expensive. To help alleviate this problem, attempts have been made to manufacture filters using a micro-electro-mechanical system method. This leads to a switchable filter system but requires two different filter structures to be built with a diode for use as a switch to switch the signal path from one filter structure to another. Drawbacks to this design include that the process used to make these filters is complicated, that the resultant filter structure is large, and that there is interference between the two filter structures.
Another approach is to use coplanar waveguide filters. Coplanar waveguide filters are manufactured by using a substrate covered with a metal layer. The metal is etched to layout various filter configurations. While small filters can be manufactured in this manner, a switchable filter system still requires two different filters connected by a diode switch. This results in a large structure.
What is needed is a filter that can combine both coplanar waveguide filters with micro-electro-mechanical switches.