Cross-Coupled Oscillator Design Using Open-Loop Technique

The paper presents a method for design of LC cross-coupled oscillators based on open-loop technique and its practical application leading to a high frequency CMOS oscillator prototype. Thanks to the proposed approach, main circuit parameters 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 10 GHz from 0.5 V power supply achieving SSB phase noise of -113 dBc/Hz at 1 MHz offset from the carrier. Low power consumption of 1.09 mW RMS, has been obtained by biasing the oscillator devices to operate in class-B i.e. VGS =Vth.