A 2.4GHz wide tuning range VCO with automatic level control circuitry

This paper presents a VCO with automatic level control circuitry. This feedback mechanism helps to keep the VCO at an optimum level for best phase noise performance over temperature, process and frequency variations. The VCO was fabricated in a 50GHz SiGe BiCMOS process. It uses MOS varactors to achieve a 600MHz tuning range. The phase noise of the VCO was measured to be -97dBc/Hz at 100kHz offset from the carrier. This number was constant to within a couple of dB under all conditions. The VCO drew approximately 4mA from a 3.3volt supply.