Electronically tunable current-mode low-pass filter

This paper deals with the application possibility of the digitally programmable current follower in analogue signal processing. In connection with conventional double- and multiple-output current followers a current-mode low-pass filter is proposed. Using digitally programmable current followers the natural frequency of the proposed filter can be electronically adjusted. The advantage of the proposed structure is that to all nodes functional grounded capacitors are connected or they are at low impedance and virtually grounded. Hence, any parasitic capacitance will cause poles or zeroes at very high frequencies. The behaviour of the designed biquad has been verified by Spice simulations and, furthermore, by experimental measurements.