Patent ID: 8305115

Claim:
A method of reducing boundary value spurs in a signal synthesizer comprising: determining initial division ratios in a frequency divider for a phase locked loop driven by a first frequency reference source (FREF 1 ) to enable the output (Fo) of the signal synthesizer to operate over a defined range of frequencies; identifying boundary spurs within the defined range of frequencies associated with a first set of division ratios in the initial division ratios to provide first frequencies in the output frequencies where boundary spurs do not occur; determining second division ratios for second frequencies in the defined range of frequencies where boundary spurs were identified using the initial division ratios, the second division ratios provided using a second frequency reference source (FREF 2 ) operating at a different frequency than the first frequency reference source (FREF 1 ) so that boundary value spurs do not occur; and controlling operation of the signal synthesizer over the defined range of frequencies so that the first frequency reference source (FREF 1 ) and first division ratios are applied for the first frequencies, and the second frequency reference source (FREF 2 ) and second division ratios are applied for the second frequencies.