Broadband Colpitts VCO for TV Tuner

Broadband Colpitts VCO for TV Tuner

The high performance of modern set-top DBS TV tuners require broadband voltage control oscillator (VCO) designs at a competitive cost. To realize these goals, design engineers are challenged to create high performance, low-cost VCOs.

The traditional design of Colpitts oscillator is used for many VCO applications. Designing a broadband Colpitts oscillator with coverage from 1–2 GHz requires the selection and interaction of an appropriate varactor diode for its resonator. This design describes a broadband Colpitts VCO that incorporates the SMV1265-011 varactor diode.
 
 

Broadband Colpitts Variable Controll Oscillator 1-2 GHz Schematic

Broadband Colpitts Variable Controll Oscillator 1-2 GHz PCB Layout

This varactor diode was specifically developed at Alpha for this application. The VCO design, based on Libra Series IV simulation, shows good correlation between measured and simulated performance. This application note includes a board layout and materials list.
More info: A Colpitts VCO for Wideband (0.95–2.15 GHz) Set-Top TV Tuner Applications
 
http://www.ziddu.com/download/9053779/1-2ghzvco.pdf.html