Current-mode fractional-order shelving filters using MCFOA for acoustic applications

Abstract

In this study, low-pass and high-pass current-mode fractional-order shelving filters were designed for use in acoustic applications. The filter’s architecture has two main components, Modified Current Feedback Operational Amplifier (MCFOA) active block structure based on Bipolar Junction Transistors (BJTs) and a minimum number of only grounded passive elements. These components enable the filter to operate in current-mode and low voltage/power applications. The grounded capacitor design uses a 5th-order Oustaloup approximation and a properly configured Foster type-I RC network. The main advantage of the fractional-order shelving filters is that they provide an extra order of freedom in the transition slope from the passband to the stopband, improving the listening experience. In this paper, a new approach of using an MCFOA structure to design the fractional-order filters that operate in current-mode is presented. The filters provide current-mode circuit advantages such as wide dynamic range, low noise, low THD and are suitable for low voltage/power applications. The results from theoretical calculations, along with simulations of the filters were compared and verified. From the obtained data, it was observed that the cut-off frequency of 2 kHz is suitable to be used in acoustic applications.