Amplitude Control of Twin-T and Phase-Shift Oscillators Based on Direct Feedback Control Technique

Abstract

This article presents a simple circuit design for control the amplitude value of the Twin-T and the Phase-Shift oscillators. The proposed circuit design uses feedback control technique to control the oscillator directly without multiplier circuit. The structure of the designed system consists of a target oscillator, an offset eliminator, an amplitude detector, and an error integrator to generate direct current-type (DC) voltages of the target oscillator. Both the Twin-T and the Phase-Shift oscillators can adjust amplitude value by using an external control signal. Experimental results verifying performance of the designed circuit by using direct feedback control technique agreed with expected values.Keywords: Oscillator, amplitude control, feedback control, second-order oscillator, multi-time variable technique.