Continuously Tunable Active-ROscillator with Two Operational Amplifiers

摘要

A new oscillator circuit with two operational amplifiers (OAs) and six resistors, which is attractive for monolithic IC fabrication is presented. It can be made to oscillate by adjusting a resistor ratio while its frequency can be independently controlled over a wide range, by a grounded resistor, say by the source-to-drain resistance of an FET whose source-to-gate voltage is varied. Such an arrangement results in a voltage-controlled oscillator. Circuits of resistor-and voltage-controlled oscillators were built and tested. There is an excellent agreement between calculated and experimental results. The salient features of the new oscillator are: (a) Oscillations over a wide frequency range, (b) Constant amplitude of oscillations, (c) Low distortion of waveshape and (d) Independent frequency control through a grounded resistor which can lead to a voltage-controlled oscillator (VCO).