VHF bandpass filter design using CMOS transresistance amplifiers

A linear wideband class AB transresistance (Rm) amplifier is proposed and analyzed. Using the Rm amplifier, a new transresistance-capacitor (Rm-C) differentiator is designed. Considering the intrinsic capacitances of the MOS transistors as filter elements, the Rm-C configuration can be regarded as a very high frequency (VHF) bandpass biquad filter with the center frequency mainly depending on the differentiating capacitor value. The center frequency can be finely tuned by varying the r_m value of the tunable Rm amplifier. Without loading degradation, cascading the Rm-C biquads can enhance the quality factor Q of the filter. Simulation results indicate the capability of the proposed new filter implementation method to realize a VHF bandpass biquad with the center frequency as high as 100 MHz