1/f2Phase Noise Analysis in Active-Coupling LC-Tank Oscillators With Frequency Mismatch

Multi-core LC-tank oscillators have attracted a great deal of attention since their capability to achieve ultra-low phase noise in a scalable and power-efficient way. This brief presents a study of 1/f2 phase noise in active-coupling oscillators. A complete frequency domain analysis is proposed to describe the steady-state oscillators amplitude and phase. Closed-form formulas are derived for phase noise degradation caused by resonance frequency mismatches between the LC-tanks. The theoretical analysis is first validated through extensive simulations and then exploited to compare the robustness to LC-tank frequency mismatches in active- and resistive-coupling oscillators, proving the superior performance of the latter.