Designing wideband voltage controlled oscillators for Software-Defined Radio

The demand for mobile communication systems with global coverage, interfacing with various standards and protocols, high data rates and improved link quality for a variety of applications has dramatically increased in recent years. The Software-Defined Radio (SDR) is the recent proposal to achieve these. In SDR, new concepts and methods, which can optimally exploit the limited resources, are necessary. One very important requirement of SDR is designing wideband RF hardware covering octave bands. For example, the local oscillator of the mixer should be a wideband voltage controlled oscillator (VCO). The paper presents theoretical concepts for designing VCOs. It also provides simulation of the design. Using this conceptual design and simulation, the actual VCO hardware was designed and fabricated, and the results including very good phase noise performance are presented.