The SA8025 is a 3V, 1.8GHz, SSOP 20-pin packaged fractional-Nphase locked-loop (PLL) frequency synthesizer. It is targeted forsystems like the Japan Personal Handy Phone System (PHS,formerly PHP) which demands fast switching time and good noiseperformance. Built on the QUBiC BiCMOS process, it has phasedetectors with maximum frequency of 5MHz and an auxiliarysynthesizer that can operate up to 150MHz. This design was basedon the UMA1005 (all CMOS), an earlier version fractional-Nsynthesizer which requires an external prescaler for 1 and 2GHzapplications. There is also a 1GHz version fractional-N PLLfrequency synthesizer, the SA7025, available for systems operatingunder 1GHz. One should expect the performance of the SA8025and SA7025 to be comparable to the UMA1005 with an extraprescaler. This application note will serve as a supplement to theapplication note for the UMA1005 (Report N SCO/AN92002) or asa stand-alone document specifically for the SA8025.