Electronically tunable current-mode multifunction filter using current-controlled current follower transconductance amplifier

Montree Kumngern ,Fabian Khateb ,Pipat Prommee ,Winai Jaikla

doi:10.33180/infmidem2019.303

Abstract

A new electronically tunable current-mode multifunction universal filter with three inputs and one output based on current-controlled current follower transconductance amplifier is presented. The proposed filter can realize low-pass, band-pass, high-pass, band-stop and all-pass filtering functions into single topology. For realize these filtering functions, no passive component-matching conditions, no inverting-type input signal requirements and high-output impedance are possessed. Also the proposed filter offers electronic control of the natural angular frequency, low active and passive sensitivities and use of grounded capacitors which is ideal for integrated circuit implementation. The proposed universal biquadratic filter has been used to realize sixth-order filters. PSPICE simulation results are used to confirm the presented theory.

Highlights

The universal biquadratic filters are classified as second-order filters that typically implement five filtering functions with a single topology such as low-pass (LP), band-pass (BP), high-pass (HP), band-stop (BS) and all-pass (AP) transfer functions
Considering the input and output terminals, these filters can be classified in three categories, that are a single-input multiple-output (SIMO) filter, a multiple-output singleinput (MISO) filter and a multiple-input multiple-output (MIMO) filter
When a single signal is applied at the input of a SIMO filter, filtering functions such as LP, BP, HP, BS and AP functions can be obtained at each output terminal

Summary

Introduction

The universal biquadratic filters are classified as second-order filters that typically implement five filtering functions with a single topology such as low-pass (LP), band-pass (BP), high-pass (HP), band-stop (BS) and all-pass (AP) transfer functions. The reported filters suffer from one or more of the following disadvantages: (i) lack of electronic tuning capability [50,51,52], (ii) use of either floating capacitors or floating resistors [50,51,52,53], (iii) cannot provide five standard filtering functions [50], [53], [54], (iv) do not exploit the full capability of the active device when the y-terminal of the current conveyor is not used [55]. VCC compared with the filters using a single active element in [47,48,49,50,51,52,53,54,55], the proposed filter provides five standard filtering functions, electronic tuning capability, the use of grounded capacitors and high-output impedance

Circuit realization

Non-ideal analysis

Application to sixth-order filters

Simulation results

Findings

Conclusions