Low-sensitive CCII-based biquadratic filters offering electronic frequency shifting

Two novel filter implementations offering electronic frequency shifting are presented. In particular, the first implementation realizes the complete biquadratic function, while the second gives simultaneously high-pass, low-pass, and bandpass second-order transfer functions. The filters are constructed by CCIIs, two of which have tunable current gain employed for frequency shifting. Moreover, we propose design procedures which keep most of the passive and active sensitivities to low values, while diminishing the influence of the parasitic elements existing at the CCII terminals on filter frequency response. The performance of the proposed filters and the effectiveness of the design procedure in minimizing the parasitics effects were examined by PSPICE simulation.