A 39-GHz On-Chip Bandpass Filter using Coupled-Line Structure in 130-nm SiGe Technology

In this paper, a design methodology is presented to generate transmission zeros (TZs) for a bandpass filter (BPF) at both lower and upper stopbands. As a result, the selectivity and the stopband suppression performance can be improved. Using this method, the TZs can be generated in a very flexible way. As proof of concept, a 39-GHz bandpass filter (BPF) is fabricated in 130-nm SiGe technology. Including the pad loss, the measured insertion loss is less than 3.5 dB, and the lower-stopband suppression is greater than 20 dB from DC to 31 GHz. Besides, the footprint, excluding the pads, is only 0.031 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>.