Application Note

RSS

Like all RF and microwave components, a differential filter design will remain only a simulation exercise if it is not created with its manufacturing process in mind. That is, the tight dimensional tolerances required to meet a set of performance goals must be within the capabilities of the filter's manufacturing process in order to realize a reliable, repeatable filter. Geometries that are difficult to manufacture, such as very wide lines with very narrow gaps or very narrow lines with very wide gaps, are typically accompanied by extreme resonator impedance swings. A filter synthesis tool must be able to automatically manage these impedances using analytical and empirical techniques (such as Norton and Kuroda transforms, and m-derived and constant-k end sections) to mitigate extreme impedances and produce geometries that can be easily realized. A hairpin bandpass filter with a target center frequency of 5.8 GHz will be used in this application note as an example to illustrate how this can be accomplished using AWR's Microwave Office™ software with iFilter technology to synthesize the structure, and then AWR's AXIEM® 3D planar electromagnetic (EM) solver to validate it.