A novel balanced filter circuit with wideband common mode suppression using coupled lines is proposed in this paper. A wideband filter with half open stubs is used to realize two transmission zeros for the differential mode passband. The common mode can be suppressed over 15 dB from 0 GHz to 3f0 (f0 is the center frequency of the passband) with insertion loss greater than 15 dB over the upper stopband. A balanced filter with 3-dB fractional bandwidths of 38% is designed and fabricated. Good agreement can be observed between measured results and theoretical expectations.
"Wideband Balanced Filters with Wideband Common Mode Suppression Using Coupled Lines," Progress In Electromagnetics Research Letters,
Vol. 65, 49-55, 2017. doi:10.2528/PIERL16111201
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