Charge-Pump Folded Noise Cancelation in Fractional-N Phase-Locked Loops

Author

Gaied, David ; Hegazi, Emad

Author_Institution

Intel Mobile Commun., Cairo, Egypt

Volume

61

Issue

6

fYear

2014

fDate

41791

Firstpage

378

Lastpage

382

Abstract

In this brief, we propose a technique for Delta-Sigma (ΔΣ) noise cancelation in fractional-N phase-locked loops (PLLs). The proposed method performs noise cancelation for both the shaped noise generated by the ΔΣ modulator and the downfolded noise due to charge pump (CP) nonlinearity. By precoding the CP control pulses, the added hardware complexity is minimal compared with conventional cancelation, whereas noise reduction is large. The proposed method is verified through the system design of a 2.5-GHz ΔΣ fractional-N PLL. Time-domain simulations show 20-dB noise reduction for the downfolded noise when applying the proposed cancelation.

Keywords

charge pump circuits; delta-sigma modulation; phase locked loops; charge pump folded noise cancelation fractional-N phase locked loops; delta sigma noise cancelation; frequency 2.5 GHz; hardware complexity; Charge pumps; Noise cancellation; Phase locked loops; Phase noise; Quantization (signal); Voltage-controlled oscillators; Charge pump (CP); Delta??Sigma $(DeltaSigma)$ modulation; PLL; fractional-N phase-locked loop (PLL); noise cancelation; phase frequency detector (PFD);

fLanguage

English

Journal_Title

Circuits and Systems II: Express Briefs, IEEE Transactions on

Publisher

ieee

ISSN

1549-7747

Type

jour

DOI

10.1109/TCSII.2014.2319691

Filename

6804654