Phase Noise Analysis of Periodically ON/OFF Switched Oscillators

The paper presents a detailed analysis of phase noise in periodically switched oscillators (PSOs) which are emerging as effective multipliers in mmW applications. The analysis shows that the output phase noise of these stages cannot be estimated using the analogy to retimed oscillators. Closed form expressions for the transfer of both the reference and the oscillator noise are derived together with a correction to include the contribution of the oscillator close-in phase noise. The results are validated against Cadence Spectre RF® simulations of a PSO designed in a 28-nm bulk CMOS technology. The excess noise arising from the finite duration of the on-off transients is also discussed.