Synthesis of New Single CFOA-Based VCOs Incorporating the Voltage Summing Property of Analog Multipliers

S S Gupta,R Senani,D R Bhaskar

doi:10.5402/2012/463680

Abstract

Recently, current feedback operational amplifier (CFOA) and analog multiplier-(AM-) based-voltage controlled oscillators (VCOs) have been published in the literature which require 2 CFOAs and 2 AMs for linear tuning law between control voltage and frequency of oscillation. In this paper, a family of eight new voltage-controlled oscillators (VCOs), with linear tuning laws, employing only a single CFOA in conjunction with two analog multipliers (AMs), has been derived through a systematic state-variable methodology. This has been made possible by exploiting the voltage summing property of the multiplier chosen which has never been done in the literature earlier. The workability of the presented VCOs has been verified by experimental results based on AD844 type CFOAs and AD534 type AMs, and the advantages of new circuits over the previously known CFOA-AM-based VCOs have been highlighted.

Highlights

A number of new building blocks and concepts related to current-mode circuits have been investigated in the literature [1,2,3], the use of current feedback operational amplifiers (CFOAs) as an alternative to the traditional voltage-mode op-amps (VOAs) has attracted considerable attention in various instrumentation, signal processing, and signal generation applications due to their commercial availability as off-the-shelf ICs as well as due to the well-known advantages offered by CFOAs over the VOAs [4,5,6]
We have presented a systematic derivation of eight new CFOA-analog multipliers (AMs)-based voltage-controlled oscillators (VCOs), providing linear tuning laws
The workability of the new VCOs has been confirmed by the experimental results, based upon AD844 type CFOAs and AD534 type analog multipliers

Summary

Introduction

A number of new building blocks and concepts related to current-mode circuits have been investigated in the literature [1,2,3], the use of current feedback operational amplifiers (CFOAs) as an alternative to the traditional voltage-mode op-amps (VOAs) has attracted considerable attention (see [4,5,6,7] and the references cited therein) in various instrumentation, signal processing, and signal generation applications due to their commercial availability as off-the-shelf ICs as well as due to the well-known advantages offered by CFOAs over the VOAs [4,5,6]. The advantages of the new CFOA-based VCOs as compared to the previously known CFOA-based VCOs are highlighted

Proposed VCO Configurations

C2R2R3

Consideration of CFOA Parasitics

Experimental Results

C1C2R2R3

Concluding Remarks