Si53xx-RM

5. DSPLL (All Devices)

All members of the Any-Frequency Precision Clocks family incorporate a phase-locked loop (PLL) that utilizes Silicon Laboratories' third generation DSPLL technology to eliminate jitter, noise, and the need for external VCXO and loop filter components found in discrete PLL implementations. This is achieved by using a digital signal processing (DSP) algorithm to replace the loop filter commonly found in discrete PLL designs. Because external PLL components are not required, sensitivity to board-level noise sources is minimized. This digital technology provides highly stable and consistent operation over process, temperature, and voltage variations.

A simplified block diagram of the DSPLL is shown in Figure 20. This algorithm processes the phase detector error term and generates a digital frequency control word M to adjust the frequency of the digitally-controlled oscillator (DCO). The narrowband configuration devices (Si5316, Si5319, Si5323, Si5324, Si5326, Si5327, Si5366, Si5368, and Si5369) provide ultra-low jitter generation by using an external jitter reference clock and jitter attenuation. For applications where basic frequency multiplication of low jitter clocks is all that is required, the wideband parts (Si5322, Si5325, Si5365, and Si5367) are available.

 

 

DSPLL

 

 

 

fIN

Phase

Digital Loop

M

Digital

Fvco

 

Detector

Filter

 

DCO

 

fOUT

Figure 20. Any-Frequency Precision Clock DSPLL Block Diagram

46

Rev. 0.5

Page 46
Image 46
Silicon Laboratories SI5365, SI5369, SI5366, SI5367 Dspll All Devices, Any-Frequency Precision Clock Dspll Block Diagram