MODELING PHASE NOISE IN FREQUENCY-DIVIDERS

Many modern electronic systems employ Frequency synthesizers whose spectral purity is critical. Although the noise in the digital frequency dividers commonly contained in these synthesizers affects that purity, it is not adequately modeled in terms of parameters that are useful for synthesizer design. A theory for modeling such noise and measurements to support the theory are presented. The most complete measurements were made on ECL dividers for which the primary noise contributions were from additive output noise and sampled additive input noise. Output phase power spectral density due to the latter varies as the square of the input frequency and is inversely proportional to the output frequency. The third most significant contributor was sampled output noise. A summary of presently available noise data is also given. © 1990 IEEE