A 3GHz low power, MOS varactor voltage controlled oscillator for implantable ultra wideband applications in CMOS Silicon-On-Sapphire (SOS) process

For transceiver design in low cost CMOS technologies, one of the most challenging elements is the voltage controlled oscillator (VCO), especially if designed for low power. A VCO has been designed and measured where a MOS transistor is used as a varactor, as part of strategy to obtain the wide tuning range of 500MHz. Phase noise was measured and found to be -111dBc/Hz at 1MHz offset at an oscillation frequency of 3.2GHz. The VCO, implemented in 0.25μm Silicon on Sapphire (SOS) CMOS, consumes 600μW of DC power from a 1.2V source and is suitable for implantable UWB applications.