Compact Low-Loss Wideband Differential Bandpass Filter With High Common-Mode Suppression

Wideband Balanced Filters With Wideband Common Mode Suppression Using Coupled Lines

“…Table 2 illustrates the comparisons of measured results for different balanced filters. Compared with other balanced filters [3][4][5][6][7][8][9][10][11][12][13][14][15], the balanced filter can keep the wideband common mode suppression, and more transmission zeros close to the differential mode passband can be achieved to improve skirt selectivity. Moreover, to further extend the bandwidth of the balanced filter, patterned ground-plane technology [7] can be introduced to the balanced bandpass filter.…”

“…In the past few years, many microstrip balanced filters for single-band, dual-band and wideband with common mode suppression have been realized [3][4][5][6][7][8][9][10][11][12][13][14][15]. In [5,6], branch-line couplers are cascaded to realize a wide passband for the differential mode; however, out-of-band common mode suppression cannot be solved.…”

“…In [5,6], branch-line couplers are cascaded to realize a wide passband for the differential mode; however, out-of-band common mode suppression cannot be solved. Broadside coupled microstrip-slotmicrostrip structures can also be utilized to realize an ultra-wideband (UWB) differential filter in [7][8][9][10], but the transmission zeros near the differential mode passband are difficult to increase. Some ultra-wideband (UWB) balanced bandpass filters based on double-sided parallel-strip lines (DSPSLs) are introduced in [11,12], but the upper stopband for the differential mode should be further extended.…”

“…Therefore, when the coupled circuits of Fig. 1 are used to design balanced filters, the symmetrical shorted stubs can be used to design a high selectivity passband for the differential mode, and the asymmetrical open/shorted stubs can be used to suppress common mode over a wide band, and the asymmetrical circuit model can have more freedom to design different balanced circuits, which are different from former balanced circuits in [3][4][5][6][7][8][9][10][11][12][13][14][15]. Moreover, some other stubs can also be considered to increase the passband order and transmission zeros for the differential mode [16], and the increased transmission zeros can be used to further improve the common mode suppression.…”

Automated design of balanced wideband bandpass filters based on mirrored stepped impedance resonators (SIRs) and interdigital capacitors

“…The design of differential-mode (or balanced) wideband bandpass filters with common-mode noise suppression is a very active research topic today [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. These filters are fundamental elements in balanced circuits and systems (e.g., high-speed digital circuits), of increasing demand for their inherent high immunity to noise, electromagnetic interference (EMI) and crosstalk.…”