Auxiliary Feed-Forward Noise Cancellation Techniques for a Generic Type-II Ring Oscillator Phase Locked Loop

This brief presents an auxiliary feed-forward noise cancellation (AFFNC) technique that can be applied to a generic Type-II ring oscillator (RO) PLL. The AFFNC technique uses a stand alone sub-sampling phase detector (SSPD) embedded into an alignment loop to extract and cancel noise from the RO output. Along with AFFNC, which uses one reference edge for noise extraction, a Double Sampled AFFNC (DS-AFFNC) which utilizes both the rising and falling edge of the reference for noise extraction is also presented. By using both the reference edges, higher cancellation bandwidth is achieved in DS-AFFNC. The phase-domain model developed for AFFNC and DS-AFFNC show a 2.9x and 3.9x integrated jitter reduction respectively.