PLL is an automatic control system adjusting controlled oscillator frequency to be equal to reference oscillator frequency multiplied by a given integer. Frequency adjustment is carried out by using negative feedback. A phase detector compares a controlled oscillator output with a reference signal. The result is a charge pump current output that supplies external feedback filter and converted to a voltage for controlled oscillator adjustment.
Clock divider is used to generate signals with specified frequency. Delta-sigma modulator makes it possible to operate with reference oscillator of different frequency.
The block is fabricated on SMIC CMOS 0.18 um technology.