Design of Novel Precise Quadrature Oscillators Employing ECCIIs with Electronic Control

In this paper, an interesting design of precise quadrature oscillator employing electronically controllable current conveyors of the second generation (ECCII) is presented. The main purpose of this paper is to show advantages and features of direct electronic control of application by an adjustable current gain where help of signal flow graph approach was used to clearer and visual understanding of the design. The discussed circuit and its presented modification have several favorable features such as grounded capacitors, independent electronic adjusting of oscillation frequency and condition of oscillation by the current gain and easy automatic gain control circuit (AGC) implementation (non-ideal effects of tuning process on output amplitudes are suppressed). Oscillator was designed for frequency band of units of MHz and tested with two types of inertial AGCs. Theoretical presumptions were confirmed by laboratory experiments.