A wide tuning range and constant gain VCO for radio frequency application

A wide-tuning-range and constant gain ring voltage controlled oscillator (VCO) is presented for radio frequency application. The circuit is implemented in 90nm RF CMOS 1.2 V process technology. The biasing circuit utilizes the concept of voltage controlled voltage source to increase the tuning range as well as to obtain a constant gain (KVCO) within the operating range. This results in a rail-to-rail control voltage (0 V-1.2 V). The oscillation frequency of the designed VCO ranges from 2.42 GHz to 12.12 GHz (S band to X band). The 1 MHz offset phase noise of the VCO for an output frequency of 12.12 GHz is found to be -78.87 dBc/Hz without applying any phase noise reduction technique. The circuit consumes a very low power of 2.47 mW at the maximum operating frequency of 12.12 GHz from a power supply of 1.2 V. The layout of the whole VCO circuit occupies an area of 0.001 mm2.