All-pass filter for rich cascadability options easy IC implementation and tunability

This paper presents two current-mode all-pass sections, employing only grounded components, which is important from the integrated circuit (IC) implementation point of view. The use of the grounded capacitor allows the IC implementation with standard CMOS technologies. The circuits can be made electronically tunable due to grounded resistors that can be realized by using voltage controlled MOS based resistors. In addition, the circuits have both low input impedance and high output impedance for easy cascadability. The stability analysis proves that the circuits are stable. SPICE simulations and experimental results are in close agreement with the theory.