The active-bridge oscillator

This paper describes the Active-Bridge Oscillator (ABO), a new concept in high-stability oscillator design. The ABO is a bridge-type oscillator design that is easy to design and overcomes many of the operational and design difficulties associated with “standard” bridge oscillator designs. The ABO will oscillate with a very stable output amplitude over a wide range of operating conditions without the use of an automatic-level-control (ALC). A standard bridge oscillator design requires an ALC to maintain the desired amplitude of oscillation. For this and other reasons, bridge oscillators are not used in mainstream designs. Bridge oscillators are generally relegated to relatively low-volume, high-performance applications. The Colpitts and Pierce designs are the most popular oscillators but are typically less stable than a bridge-type oscillator. The ABO is a highly integrable circuit and can be designed for use over a very wide frequency range with only minor circuit variations. The high Q of this design can dramatically improve phase-noise, reduce power-supply sensitivity, and minimize circuit related pulling problems common to most popular oscillator designs. The design intention of the ABO is not to make a state-of-the-art bridge-type oscillator but to provide a practical high-performance alternative that delivers most of the performance advantages of a bridge oscillator without the inherent disadvantages of complexity, design difficulty, high-power requirements, and integration potential