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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 $$I\hbox {/}Q$$ -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 $$\pm 20^\circ $$ , 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 $$0.18\,\upmu \hbox {m}$$ TSMC CMOS technology. [ABSTRACT FROM AUTHOR]

In this paper, a novel LC quadrature oscillator (QO) is presented that can simply and automatically cancel the phase and amplitude errors raised by mismatches in LC tanks; the major source of phase and amplitude errors. The design is based on method of using unequal coupling factors in a parallel quadrature oscillator (P-QO). This method shows how we can cancel phase and amplitude errors simultaneously by choosing appropriate inversely proportional coupling factors. To cancel the errors, the proposed circuits first sense the phase error and increase or decrease the difference between the coupling factors accordingly. When tuning tail currents, the coupling factors can be simply adjusted. The entire system has a block diagram like a PLL. The dynamics of the proposed circuit is analyzed, and it is shown how the phase and amplitude error is canceled in response to an imposed LC tank mismatch. To evaluate the circuit, a QO has been designed to oscillate at 5 GHz with 1.8 V supply and 6.2 mA current consumption. The circuit has been simulated using TSMC 0.18 CMOS practical model where all the results confirm the analytical results. [ABSTRACT FROM AUTHOR]

Using an analytical approach, new estimation of phase error in LC-Tank quadrature oscillators is proposed. The mismatches between passive components of LC tanks are considered as the reasons of the phase error. Closed form equations relating LC mismatches to phase errors are presented. Decreasing quality factor (Q) and increasing coupling factor (k) causes phase error be less sensitive to mismatches in LC tanks. On the other hand phase noise is inversely proportional to quality factor (Q), and directly proportional to coupling factor (k), so there is a tradeoff between phase noise and phase error. To evaluate the analysis, a 5 GHz quadrature LC-Tank oscillator is simulated using TSMC 0.18 μm model technology. The results confirm the simplicity and high accuracy of the proposed analysis. [ABSTRACT FROM AUTHOR]