Tunable low-pass MEMS filter using defected ground structures (DGS)

• The tunable lowpass filter with DGS structure was fabricated using MEMS technology.
• The cut-off frequency and the insertion loss of the filter were studied.
• The filter fabrication was shown and the filter has small chip size of 2.5 mm × 1.2 mm.

A tunable bandstop filter applying the micromachined technology is designed, simulated and fabricated. The filter is realized by incorporating defected ground structures structures with the micromachined switches. The surface micromachining fabrication process is employed on the high resistivity silicon substrate to fabricate the filter. The measured 3-dB cut-off frequency changes of the reconfigurable low-pass filter for four different states has been analyzed. The measured insertion loss is very lower in four tuning range of the filter. This work demonstrates the possibility of high-performance compact-size reconfigurable filters at mm-waves using multiple-contact micromachined switches. Simulated and measured results of the proposed filter show good agreements. The entire reconfigurable filter was realized in a small chip size of 1.2 mm × 1.5 mm.