Spur Immunity in MASH-Based Fractional-N CP-PLLs With Polynomial Nonlinearities
Valerio Mazzaro, Michael Peter Kennedy
Abstract
Spurious tones appear in the output phase noise spectrum of a fractional-N frequency synthesizer when nonlinearities are present in the loop. These spurs are generated by the interaction between the nonlinearity and the quantization error that the digital Σ modulator (DDSM) introduces into the system. This paper analyzes the spurious effect of polynomial nonlinearities on fractional-N CP-PLLs equipped with multi-stage noise shaping (MASH) DDSMs of different orders. This leads to a proof of immunity from spurs for PLLs based on higher order MASH modulators in the case of certain polynomial nonlinearities.
Topics & Concepts
Noise immunitySpurious relationshipControl theory (sociology)Phase noiseNonlinear systemPolynomialQuantization (signal processing)Noise shapingPhase-locked loopSpurMathematicsNoise (video)PhysicsElectronic engineeringComputer scienceMathematical analysisAlgorithmEngineeringTelecommunicationsQuantum mechanicsStatisticsStructural engineeringTransmission (telecommunications)Artificial intelligenceImage (mathematics)Control (management)Advancements in PLL and VCO TechnologiesPhotonic and Optical DevicesSemiconductor Lasers and Optical Devices