Title :
Sub-sampling sigma-delta modulator for baseband processing
Author :
Chandrasekaran, Srinivasaraman ; Black, William C., Jr.
Author_Institution :
Iowa State Univ., Ames, IA, USA
Abstract :
A sigma-delta (SD) modulator has been developed for baseband processing in a direct conversion receiver (DCR). A second-order SD modulator with a subsampling mixer, inside the feedback loop, down-converts the incoming RF signals directly to baseband, digitizes them and attenuates noise as well as interferers. A prototype was fabricated in a TSMC 0.25 μm process for use in a CDMA2000 transceiver. SNR greater than 53 dB was measured for single-ended baseband inputs and a SNRmax of 32 dB was measured for differential inputs at 900 MHz, over a 2 MHz bandwidth
Keywords :
UHF integrated circuits; UHF mixers; circuit feedback; code division multiple access; interference suppression; land mobile radio; sigma-delta modulation; signal sampling; transceivers; 0.25 micron; 2 MHz; 900 MHz; CDMA2000 transceiver; RF signal down-conversion; SNR; baseband processing; differential inputs; direct conversion receiver; feedback loop; interference attenuation; noise attenuation; second-order SD modulator; signal digitization; single-ended baseband inputs; sub-sampling mixer; sub-sampling sigma-delta modulator; Bandwidth; Baseband; Computer architecture; Delta-sigma modulation; Digital filters; Digital signal processing; Low pass filters; Radio frequency; Signal to noise ratio; Transceivers;
Conference_Titel :
Custom Integrated Circuits Conference, 2002. Proceedings of the IEEE 2002
Conference_Location :
Orlando, FL
Print_ISBN :
0-7803-7250-6
DOI :
10.1109/CICC.2002.1012796
