A low-loss 1.4–2.1 GHz compact tunable three-pole filter with improved stopband rejection using RF-MEMS capacitors

A 1.4-2.1 GHz compact tunable 3-pole bandpass filter with improved stopband rejection using RF-MEMS capaciters and varactor diodes has been demonstrated. The MEMS capacitors are fabricated and fully packaged using a 0.18 μm CMOS standard process with integrated high voltage drivers and SPI control logic and with reliability in the billions of cycles. The 1.4 - 2.1 GHz filter results in insertion loss <; 2 dB with 1-dB fractional bandwidth (FBW) of 12-13%. The proposed design has highly improved stopband rejection compared to a standard combline filter. The application areas are in modern multi-standard communication systems.