Switched capacitor bandpass filter tuned by ring VCO in CMOS 0.35 μm

Recently Switched-Capacitor filtering capabilities have grown to the Megahertz frequency range. This paper describes an original association of a switched capacitor (SC) bandpass filter and its command circuit made up by a ring voltage controlled oscillator (VCO) with "exclusive-or" (XOR) gates. Implemented in a standard BiCMOS 0.35 μm technology, this circuit is attended to be employed in a subset of mobile phone applications using the Tetrapol standard of EADS-TELECOM, which requires a frequency range between 380 and 520 MHz. The results presented for this first design are a tunable center frequency range equal to 220 MHz (320 MHz-540 MHz), with a quality factor greater than 300.