Open loop approach to design low voltage, 400 mV, 1.3 mW, 10 GHz CMOS class-B VCO

The paper presents a method for design of LC cross-coupled oscillators based on an open loop technique and its practical application leading to a high frequency CMOS oscillator prototype. Thanks to the proposed approach, the main circuit parameters such as loaded quality factor (responsible for phase noise performance of LC oscillator) and steady-state oscillation amplitude, can be extracted without the necessity of time consuming transient simulations. The presented method is not technology specific and allows fast calculations under changing bias conditions. The proposed 130 nm CMOS prototype operates at 10 GHz from a 400mV power supply achieving an average SSB phase noise of -110 dBc/Hz at 1 MHz offset from the carrier and a fractional bandwidth of more than 7.5%. Low average power consumption of 1.3 mW RMS, has been obtained by biasing the oscillator devices to operate in class-B i.e. V_GS = V_DD = V_th.