A Quadrature Sinusoidal Oscillator With Phase-Preserving Wide-Range Linear Frequency Tunability and Frequency-Independent Amplitude

A G_m-C architecture for a quadrature sinusoidal oscillator with phase-preserving wide-range linear frequency tunability is discussed. The topology is characterized by low harmonic distortion, as well as controlled and stable amplitude of oscillation that is independent of the oscillation´s frequency and instantaneous frequency changes. The architecture has been implemented for acoustic sonar applications using general-purpose discrete bipolar transistors. The phase-preserving frequency control makes the architecture appropriate for continuous-phase frequency-shift keying modulators as well. Measurements and simulation results are presented and found in good agreement with theory