| Filters are classified as: low pass, high pass, band-pass and band-stop. Band-stop filters are one of the key components in the RF front end of a microwave communication system. Band-stop filters or notch filters are useful to avoid unwanted signals and interference. The interfering signals may have shifting frequencies and therefore the tenability of bandpass is extremely important. Although a variety of tunable devices are available, recently ferroelectric capacitors are attracting the attention of many investigators, because of their high speed, polarity independent voltage tenability, small size, substrate independent integration, and absence of moving parts. In addition, present and future communication systems operate in multiple bands. Therefore there is necessity for dual and multiband filters. The Dual Band Band-Stop Filter (DBBSF) is an important circuit component in microwave applications. DBBSFs are commonly employed in high power amplifiers and mixers to suppress the double sideband spectrum to reduce circuit size and cost. Design of Dual Band filters at microwave frequencies is still challenging since it has to take into consideration many parameters, including center frequency, bandwidth, tenability, return loss, and insertion loss. This dissertation focus on the implementation multi-band stop filters using ferroelectric capacitors. |
