Third-order quadrature sinusoidal oscillators with fully uncoupled tuning laws using only two CFOAs and grounded capacitors

Abstract

Recently, three current feedback operational amplifiers (CFOA)-based third-order quadrature sinusoidal oscillators (TOQSO) have been presented whose condition of oscillation (CO) and frequency of oscillation (FO) can be regulated independently. In this communication, we present two new TOQSO circuits, which require only two CFOAs and yet achieve as significant features as the quoted circuits, namely, the availability of fully uncoupled control of CO and FO, availability of both outputs from ideally zero output impedance nodes (which is beneficial for easy cascadability in VM operations) and employment of all (three) grounded capacitors as preferred for IC implementation. The verification of the workability of proposed circuits has been carried out experimentally using commercially available off-the-shelf ICs AD844-type CFOAs, and some experimental results have been appended.