Download this article in .PDF format This file type includes high-resolution graphics and schematics when applicable. | RF/microwave simulation software has become an increasingly important aspect of today’s design process. Anyone tasked with designing RF/microwave filters knows how critical software is in meeting design goals, especially in terms of customization. Today, a variety of software tools is available to help achieve those filter-design objectives.
One effective approach is the direct-synthesis technique, which enables a designer to manage the location of transmission zeros. As a result, filters are able to be designed with customized rejection responses.
This article discusses how Genesys software from Keysight Technologies can be used to design filters with the direct-synthesis technique. A lowpass filter example is also presented to illustrate the software’s capabilities.
Transmission Zeros
Transmission zeros are frequencies in which there is no signal transmission. A lowpass filter has transmission zeros at infinite frequency, while a highpass filter has transmission zeros at dc. A bandpass filter contains transmission zeros at both dc and infinite frequency.
Finite-frequency transmission zeros (FTZs) are transmission zeroes at frequencies aside from dc and infinite frequency. They can be incorporated into a filter to reject signals at specific frequencies. In other words, FTZs allow unwanted frequencies to be “notched out.” FTZs essentially shape a filter’s stopband response.
S/Filter Synthesis Program
Genesys software can be applied to create both lumped-element and distributed filters. Users can design classic filter types, such as Butterworth, Chebyshev, etc., as well as filters beyond those traditional methods.