High-Q CMOS LC pseudo switched-capacitor bandpass filter with center frequency tuning

The design of a new high-Q LC pseudo switched-capacitor bandpass filter is presented. The proposed filter is tuned by using a command circuit made up by a ring voltage controlled oscillator (VCO) with 'XOR' gates. Fabricated in a standard 0.35 mum CMOS, this circuit is intended to replace the SAW filters in wireless broadband applications. Measured results demonstrate interesting performances; a tunable center frequency range of 285 MHz [240-525 MHz] and a quality factor that can be as high as 300 within the tunable frequency range