New current mode biquad filters using current followers

Three new configurations for realizing the current-mode biquad filters using current followers (CF´s) are presented. They can realize the allpass, notch, lowpass, bandpass, and highpass filters. Some of the proposed circuits can be directly cascaded without buffers. Two configurations can generate two kinds of filtering functions simultaneously. The natural frequency ω_o of the proposed filters will be insensitive to the current tracking error of the CF. Experimental results that confirm the theoretical analysis are obtained