Micromachined micropackaged filter banks and tunable bandpass filters

Abstract

Low cost alternatives to conventional switched filter banks and tunable bandpass filters are investigated. Both types of filters in conventional form suffer from high cost, intricate packaging, and large weight and size. Micromachining and micropackaging were used to allow for a high performance, monolithic design on a single low cost substrate with simple conformal packaging. A micromachined micropackaged filter bank at X/Ku-band is presented. The filters are fabricated on thin dielectric membranes on silicon wafers allowing for low-loss filters on inexpensive substrates. The micropackaging provides high isolation between adjacent filters with overlapping frequency regions. Also, a novel micromachined electronically tunable filter at X-band is presented. The filter is simple to fabricate and results in a very wide tuning range with low insertion loss. An 8x microwave model was built at 1 GHz to simulate the X-band filter, and an 8 GHz filter was fabricated based on the microwave model. The filter exhibited a tuning range of over 60% for a 10% bandwidth.