Multiphase sinusoidal oscillator using inverting-mode operational amplifiers

This paper describes a simple multiphase sinusoidal oscillator based on inverting operational amplifiers (OPAs). The system comprises n cascaded inverting first-order low-pass stages and produces n odd-phase equal amplitude signals that are equally spaced in phase, from low-impedance sources. The basic scheme utilizes self-oscillation and can produce 2n even-phase signals by the inclusion of n unity gain inverters. A modified system employing signal injection through the associated phase-shifting network is also discussed. The negative feedback around the OPA´s results in extremely good frequency and distortion performances that are unmatched by other multiphase system implementations. Moreover, the system has a large output voltage swing, high current drive capacity, and utilizes readily available components