The Effect of DC Component on CMOS Injection-Coupled LC Quadrature Oscillator (IC-QO)

Abstract

This paper creates a different insight to improve phase noise of Injection-Coupled quadrature oscillators (QOs). In fact, there are several phase noise functions and the important parameter is carrier power that considered here. The QO is analyzed and the mismatches between LC tanks that are the main proofs of phase error in this oscillator are shown. The main aim of this paper is focused on the reduction of phase noise by considering DC term. It is shown that the DC level which ignored in the most previous works is also important to improve phase noise by the carrier power. With due attention in the previous equations the phase noise can be reduced and the phase error can be cancelled or controlled by adjusting bias current. On the other hand as a result, is obtained that increasing of the drain current and the voltage of LC tank decrease the phase noise and the phase error simultaneously. To confirm the proposed idea and analysis, a 5.5 GHz QO is designed and simulated using 0.18µm TSMC CMOS technology. The simulation results show confirmation of the proposed idea.