Active filters using single current conveyor
A current to voltage lowpass filter using a single CCII is proposed. This filter can absorb all finite CCII resistances and capacitances and offer both non-inverting and inverting output. Convenient compensation methods exist for gain inaccuracy and excess phase effects. The sensitivities are also very low. The filter is particularly useful for data converting and sampled-data filtering systems as it can fulfil both filtering for antialiasing or smoothing purpose and interfacing between current-mode and voltage-mode systems. We also present a current-mode filter topology using a single dual output CCII, which can realise various types of lowpass, bandpass and highpass filters. Since the output current is taken from one CCII output terminal, the structure is suitable for direct cascade for high-order filter design and less sensitive to the CCII parasitic effects compared with those taking current output from capacitor or resistor branches. Both voltage- and current-mode high-order filters can be readily realized using the proposed two filters as basic sections.