Design of Differential Type Class-AB Log-Domain Second-Order Notch Filter

In this study, a new current-mode second-order differential type class-AB log-domain notch filter is proposed. It is systematically designed using state-space synthesis method. Only transistors and grounded capacitors are required to realize the filter circuit. Three cases of the second-order notch filter were obtained; the regular notch, the lowpass notch, and the highpass notch. The center frequency, the notch frequency, the quality factor, and gain of the filter can be electronically tuned by changing external currents. PSP1CE simulations are given to confirm the theoretical analysis.