Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Design guidelines for fractional-N phase-locked loops with a high spectral purity of the output signal are presented. Various causes for phase noise and spurious tones (spurs) in integer-N and fractional-N phase-locked loops (PLLs) are briefly described. These mechanisms include device noise, quantization noise folding, and noise coupling from charge pump (CP) and reference input buffer to the voltage-controlled oscillator (VCO) and vice versa through substrate and bondwires. Remedies are derived to mitigate the problems by using proper PLL parameters and a careful chip layout. They include a large CP current, sufficiently large transistors in the reference input buffer, linearization of the phase detector, a high speed of the programmable frequency divider, and minimization of the cross-coupling between the VCO and the other building blocks. Examples are given based on experimental PLLs in SiGe BiCMOS technologies for space communication and wireless base stations.BMBF, 03ZZ0512A, Zwanzig20 - Verbundvorhaben: fast-spot; TP1: Modularer Basisband- Prozessor mit extrem hohen Datenraten, sehr kurzen Latenzzeiten und SiGe-Analog-Frontend-IC-Fertigung bei >200 GHz Trägerfrequen
