A 400-MHZ 4th-order CT bandpass ΣΔ modulator with automatic frequency tuning

Author

Loke, Wing Fai ; Oh, Chin Fong ; Xu, Yong Ping

Author_Institution

Dept. of Electr. & Comput. Eng., Nat. Univ. of Singapore, Singapore

fYear

2005

fDate

28-30 May 2005

Firstpage

24

Lastpage

27

Abstract

This paper presents the design and implementation of a high-speed continuous-time (CT) bandpass sigma-delta modulator targeted for an intermediate frequency (IF) receiver with an IF of 400 MHz for GSM/WCDMA application. The loop filters in the modulator is implemented with Gm-C Opamp integrators in biquad configuration. An automatic frequency tuning circuit is employed to reduce the effects of process and temperature variations on the centre frequency. Based on a commercial 0.35-μm SiGe BiCMOS process, the 4th-order bandpass modulator is able to obtain maximum SNRs of 77 dB and 62 dB for the signal bands of 200 kHz and 3.84 MHz, respectively, when sampled at 1.6 GHz.

Keywords

band-pass filters; cellular radio; circuit tuning; code division multiple access; modulators; sigma-delta modulation; 200 kHz; 3.84 MHz; 400 MHz; 62 dB; 77 dB; BiCMOS process; GSM application; WCDMA application; automatic frequency tuning circuit; biquad configuration; continuous-time bandpass ΣΔ modulator; intermediate frequency receiver; loop filters; Automatic frequency control; Band pass filters; Circuit optimization; Delta-sigma modulation; Frequency modulation; GSM; Multiaccess communication; Silicon germanium; Temperature; Tuning;

fLanguage

English

Publisher

ieee

Conference_Titel

VLSI Design and Video Technology, 2005. Proceedings of 2005 IEEE International Workshop on

Print_ISBN

0-7803-9005-9

Type

conf

DOI

10.1109/IWVDVT.2005.1504455

Filename

1504455