VDTA Based Electronically Tunable Voltage-Mode and Trans-Admittance Biquad Filter

Gunjan Gupta,Sajai Vir Singh,Sunil Vidya Bhooshan

doi:10.4236/cs.2015.63010

Abstract

In this paper, a biquad filter configuration based on two voltage differencing transconductance amplifiers (VDTAs) as newly active elements and only two capacitors as passive elements is proposed which can realize voltage-mode low pass (LP), band pass (BP), high pass (HP), band reject (BR) and all pass (AP) filtering responses using three voltage inputs. Simultaneously, the same configuration can also be used to obtain LP, BP and HP filtering responses in transadmittance-mode. The proposed biquad is capable of providing electronic control of quality factor independent of pole frequency through single transconductance parameter (biasing current). It also offers the advantage of low active and passive sensitivity. To support the theoretical analysis, the PSPICE simulation of the proposed circuit is done using 0.18 μm CMOS technology from TSMC.

Highlights

In the last few decades, current-mode active elements have been preferred over voltage-mode active elements in the designing of high performance continuous time analog filters [1] due to their several salient features such as inherently wider bandwidth, greater linearity, wider dynamic range, simple circuitry and low power consumptions
It has the advantage of its electronic tuning ability through two transconductance parameters; it does not need a resistor in practical applications
The single-input five-output biquad filter reported in Ref. [25] employs two voltage differencing transconductance amplifiers (VDTAs), two grounded capacitors, two grounded resistors and realizes all the five standard filtering functions, simultaneously, in voltage-mode only with feature of orthogonal electronic tunabilty of pole frequency and quality factor. Another valuable filter circuit with single-input multi-output [26] consists of two VDTAs, two capacitors and realizes only two filtering functions (LP, band pass (BP)) in voltage-mode and three filtering functions (BP, low pass (LP) and band reject (BR)) in trans-admittance-mode, simultaneously

Summary

Introduction

In the last few decades, current-mode active elements have been preferred over voltage-mode active elements in the designing of high performance continuous time analog filters [1] due to their several salient features such as inherently wider bandwidth, greater linearity, wider dynamic range, simple circuitry and low power consumptions. [25] employs two VDTAs, two grounded capacitors, two grounded resistors and realizes all the five standard filtering functions, simultaneously, in voltage-mode only with feature of orthogonal electronic tunabilty of pole frequency and quality factor. Another valuable filter circuit with single-input multi-output [26] consists of two VDTAs, two capacitors and realizes only two filtering functions (LP, BP) in voltage-mode and three filtering functions (BP, LP and BR) in trans-admittance-mode, simultaneously.

Description of VDTA and Proposed Filter Configuration

Bi μCOX

HP s2C1C2 g

Non Ideal and Sensitivity Analysis

Simulation Results

Conclusions