Micromachined Spurline Band-stop Filter

Abstract

This paper reports the design and fabrication of a membrane-supported spurline band-stop filter. The filter was fabricated using silicon bulk micromachining technique and a CMOS compatible metal/dielectric deposition RF sputtering technique. A closed-form expression of an equivalent value of dielectric constant is also derived and introduced to account for a multi-layer dielectric stack formed as a result of bulk micromachining. The proposed filter shows a better rejection performance and a wider 10-dB rejection bandwidth than the one realized on bulk silicon substrate. The proposed filter exhibits a 10-dB rejection band from 7.9-9.6 GHz with center frequency as 8.6 GHz. The measured rejection level in stop-band is better than 20 dB with maximum rejection level of 31 dB.Index Terms -Band-stop filter (BSF), spurline, dielectric membrane, and bulk micromachining.

A tunable compact bandstop filter using meander spurline and folding open stubs

“…Due to the excellent bandgap characteristics, it receives widely attention and is applied in filter designs. For example, the L-shaped spurline resonator was used to design for a compact wideband highrejection microstrip bandstop filter [5,6]. The filter using asymmetrical spurline resonator, which embed another Lshaped slot into the single L-shaped spurline resonator can provide two distinct cut-off frequencies [7].…”