VCO's in modern ECM systems

Modern voltage-controlled oscillator (VCO) technology is reviewed, particularly as it relates to ECM applications. Improvements in design of oscillator components and the oscillator itself are directly responsible for the reduced post-tuning drift (PTD) and fine-grain modulation-sensitivity variation of today's varactor-tuned sources. Significant improvements in short-term PTD have resulted from reduction in the junction temperatures of all active devices. In addition, lower long-term PTD has been achieved by advances in varactor manufacturing techniques.