A novel square-root domain realization of first order all-pass filter

Abstract

In this paper a new square-root domain first order all-pass filter based on the MOSFET square law is presented. The proposed filter is designed by using nonlinear mapping on the state variables of a state space description of the transfer function. To the best knowledge of the authors the filter is the first square-root domain first order all-pass structure designed by using state space synthesis method in the literature. The center frequency of the all-pass filter is not only attainable at megahertz frequencies but also tunable by an external bias current. The proposed filter operated 2.5 V supply voltage is constructed by current mirrors geometric mean circuits a linear transconductor circuit and a capacitor. SPICE simulations are given to approve the theoretical analysis.