Fast- Frequency Offset Cancellation Loop Using Low-IF Receiver and Fractional-N PLL

Author

Shin, Sangho ; Kim, Kyungmin ; Lee, Kwyro ; Kang, Sung-Mo

Author_Institution

Dept. of Electr. Eng. & Comput. Sci., Korea Adv. Inst. of Sci. & Technol., Daejeon

Volume

54

Issue

3

fYear

2007

fDate

3/1/2007 12:00:00 AM

Firstpage

272

Lastpage

276

Abstract

This brief introduces a simple circuit solution to secure loop stability of an analog-domain fast-frequency offset cancellation loop (OCL). The OCL is composed of a low-IF receiver, phase-domain frequency offset detector (OD), and fractional-N phase-locked loop (PLL). Since the OCL uses a phase-domain OD, a stability concern is essentially needed for its practical use. From the frequency-domain analysis, a PLL bandwidth adaptation by controlling charge-pump currents is proposed to achieve a strong stability with phase-margin of more than 60deg. Additionally, a tradeoff between the OCL accuracy and hardware complexity is discussed, and a design example is shown for the 2.4-GHz ZigBee application. With 4-MHz IF, designed for an 0.18-mum CMOS process, our circuit takes 30 mus to reject the frequency offset of +200 kHz within the accuracy of plusmn5 ppm, with 60-DFFs for a time-to-digital converter

Keywords

CMOS integrated circuits; circuit stability; detector circuits; phase locked loops; radio receivers; 0.18 micron; 2.4 GHz; 200 kHz; 30 mus; 4 MHz; ZigBee; bandwidth adaptation; charge-pump currents; fast-frequency offset cancellation loop; fractional-N PLL; frequency synthesizer; frequency-domain analysis; loop stability security; low-IF receiver; phase-domain frequency offset detector; time-to-digital converter; Bandwidth; Charge pumps; Circuit stability; Frequency domain analysis; Frequency locked loops; Hardware; Phase detection; Phase frequency detector; Phase locked loops; Stability analysis; Frequency offset; frequency synthesizer; low intermediate frequency; stability; time-to-digital converter (TDC);

fLanguage

English

Journal_Title

Circuits and Systems II: Express Briefs, IEEE Transactions on

Publisher

ieee

ISSN

1549-7747

Type

jour

DOI

10.1109/TCSII.2006.888733

Filename

4132968