Analysis and Design of a Phase-Tunable Source Injection-Coupled LC Quadrature Oscillator

This paper presents the design and analysis of phase-tunable injection-coupled quadrature oscillator (PT-IC-QO). Like other LC QOs, the mismatches between LC tanks are the main source of phase error in this oscillator. Using tail current in network coupling is novel approach to design new IC-QO. One of the advantages using added extra tail current in coupling network is control of coupling factor and also that it drastically reduces supply noise over classic IC-QO. Analysis and simulation result show that phase error can be controlled and cancelled simply by using tunable tail current in network coupling while that is difficultly controlled in the previse work. The basic idea of the presented design to reduce phase error due to tank mismatches is its compensation with an intentional mismatch between -side injection current. Based on the equations, a new tunable source-injected QO is proposed which is able to cancel the phase errors up to , without undesirable impact on phase noise. To evaluate the proposed analysis and consequent designed quadrature oscillator, a 5.4-GHz CMOS PT-QO is designed and simulated using the practical TSMC CMOS technology.