APLL Fractional-N phase locked loop frequency synthesizer is intended for SoC clock generation and embeds a reference 10MHz – 50MHz XTAL oscillator, which is also able to work as an input signal buffer in the same frequency range. The internal 2.5GHz high frequency VCO provides both excellent phase noise performance and ultra-fine frequency tuning step. The PLL is supplied from 1.8V input voltage down converted by embedded LDOs with low noise and high PSRR. The embedded Bias block provides a low noise and high PSRR voltage and current references to PMU, PLL core and XTAL blocks, as well as it outputs a voltage reference 1.0V for external purposes with up to 10uA load.