Graphical method for the phase noise optimization applied to a 6-GHz fully integrated NMOS differential LC VCO

Abstract

Abstract-This paper describes the design and the optimization in terms of phase noise of a fully integrated NMOS Voltage Controlled Oscillator (VCO) using a 0.25 µm BICMOS SiGe process. A three-dimensional phase noise analysis diagram and a graphical optimization approach is presented to optimize the phase noise of the VCO while satisfying design constraints such as tank amplitude, power dissipation, tuning range and start up conditions. At 2.5 V power supply voltage, the optimized VCO features a simulated phase noise of -118 dBc/Hz at 1 MHz frequency offset from a 6.12 GHz carrier. The VCO is tuned from 6.1 GHz to 7.9 GHz with a tuning voltage varying from 0 to 2.5 V, and a power dissipation of only 7.4 mW.

A Comparative Study of Ring VCO and LC-VCO: Design, Performance Analysis, and Future Trends

“…Conventional NMOS LC-VCO is modified, which connected tail current with a current source. This tail capacitance can minimize the tail current highfrequency portion and tail node voltage fluctuations [95], [115].…”

Design and implementation of a 6-GHz array of four differential VCOs coupled through a resistive network

“…Due to this considerations, the method presented by Hajimiri has been improved by adding a particular technique based on the obtaining of the optimum bias current of the VCO using a three dimensional phase noise representation using a parametric analysis and then, starting from this optimal current, to use the graphical optimization method proposed in [23] and adapted to our 6 GHz NMOS only LC VCO architecture. This process of modelization and optimization of the LC-VCO topology is used in [25] but the LC VCO topology is different from that used in our case which leads to a new modeling of the VCO and a new writing of the equations defining the design constraints.…”

“…For the determination of the optimum bias current of the VCO minimizing the phase noise, we exploit the following expression describing the VCO phase noise model (pn) [25].…”