New CMOS-based Resistor-less Current-mode First-order All-pass Filter Using only Ten Transistors and One External Capacitor

This paper proposes a new, compact CMOS realization of current-mode (CM) first-order all-pass filter (APF) using no external resistors. The circuit is created using only ten transistors and one external capacitor. The circuit uses lower number of transistors as compared to previously reported CM APFs using active building block (ABB) based approach. A comparison with previously reported CM APFs in terms of number of transistors and current consumption has been provided. As a design example, a 512 kHz pole-frequency (at typical process and 27oC) CM APF is designed in 40nm CMOS technology and validated through SPICE simulations.