High-Linearity 5.3-7.0 GHz 3-Pole Tunable Bandpass Filter Using Commercial RF MEMS Capacitors

A high-linearity 5.3-7.0 GHz three-pole tunable bandpass filters has been developed. Three half-wavelength resonators loaded with commercial RF MEMS capacitors are used in a sequential configuration to implement a compact tunable filter. All the inter-stage couplings are inductive type, and input and output matching networks are achieved using shunt inductors. The measured insertion loss and 1-dB fractional bandwidth are less than 5.3 dB and 510-620 MHz, respectively. The measured IIP3 is greater than 45 dBm at all tuning frequencies. The application areas are for high-linearity communication systems at C-band and IF tunable bandpass filters.