Oscillator apparatus and method with wide adjustable frequency range

Abstract

An oscillator formed from low cost discrete semiconductors and passive devices creates a linear periodic ramp of constant frequency with ramp slope based on an external voltage signal. Parameters are stable over a wide range of temperatures and variations of transistor parameters that normally degrade in extreme environments. The oscillator period can be phase and frequency synchronized to an external clock source over a wide range of frequencies. The oscillator ramp generator phase can be synchronized on a cycle by cycle basis for incorporation in power converters employing spread spectral EMI reduction techniques, multi-converter systems employing clock interleaving for distribution bus filter optimization, and resonant mode converters employing zero voltage switching techniques. Oscillator ramp rate is independent of frequency and can be synchronized to DC (inhibit) for use in ultra low power burst mode power conversion.