High-output-impedance current-mode multiphase sinusoidal oscillator employing current differencing transconductance amplifier-based allpass filters

This article presents a multiphase sinusoidal oscillator using current differencing transconductance amplifier (CDTA)-based allpass filters. The oscillation condition and oscillation frequency can be orthogonally controlled. The proposed circuit provides 2n-phase signals (n epsilon 2) that are equally spaced in phase and of equal amplitude. The circuit requires one CDTA, two resistors and one capacitor for each phase and no additional current amplifier. Owing to high-output impedances, the proposed circuit enables easy cascading in current-mode configurations. The effects of the nonidealities of the CDTA-allpass sections were also studied. The results of PSpice simulations are presented, demonstrating their consistency with theoretical assumptions.