Single CDTA-Based Current Mode All-Pass Filter and Its Applications

Neeta Pandey,Sajal K Paul

doi:10.1155/2011/897631

Abstract

This paper presents a single current difference transconductance amplifier (CDTA) based all-pass current mode filter. The proposed configuration makes use of a grounded capacitor which makes it suitable for IC implementation. Its input impedance is low and output impedance is high, hence suitable for cascading. The circuit does not use any matching constraint. The nonideality analysis of the circuit is also given. Two applications, namely, a quadrature oscillator and a highQband pass filter are developed with the proposed circuit. The functionality of the circuit is verified with SPICE simulation using 0.35 μm TSMC CMOS technology parameters.

Highlights

In filter applications pertaining to voice or audio frequency range, the magnitude characteristics play important role due to insensitivity of ear to change in phase whereas the phase characteristics dominate in video signal transmission
The main intention of this paper is to present a current mode first order all-pass filter configuration based on CDTA [4]
A detailed study of available first order current mode allpass filters based on CDTA [5,6,7,8,9,10,11] reveals that they use single CDTA and external resistors [5, 6]; two CDTAs and virtually grounded capacitor [7,8,9, 11]; the structure in [10] rely on matching constraint

Summary

Introduction

In filter applications pertaining to voice or audio frequency range, the magnitude characteristics play important role due to insensitivity of ear to change in phase whereas the phase characteristics dominate in video signal transmission. A detailed study of available first order current mode allpass filters based on CDTA [5,6,7,8,9,10,11] reveals that they use single CDTA and external resistors [5, 6]; two CDTAs and virtually grounded capacitor [7,8,9, 11]; the structure in [10] rely on matching constraint. The proposed current mode all-pass configuration uses a single CDTA called ZC-CDTA (Z copy CDTA) [12, 13] and a grounded capacitor It presents low input impedance and high output impedance and uses no matching constraint. The functionality of all the circuits has been verified with SPICE simulations using 0.35 μm TSMC CMOS technology parameters

Circuit Description

Nonideal Analysis

Applications

Simulation Results

Conclusion