Title :
A third-order sigma-delta modulator for dual-mode receivers
Author :
Rusu, Ana ; Tenhunen, Hannu
Author_Institution :
Dept. of Microelectron. & Inf. Technol., R. Inst. of Technol. Stockholm, Kista, Sweden
Abstract :
This paper presents a multibit sigma-delta modulator for GSM/WCDMA receivers. It uses a sigma-delta modulator with feedforward signal path to reduce the operational amplifiers nonlinearity effects. The improved performance of multibit topologies is exploited to reduce the oversampling ratio and to overcome stability limitations. A third-order 4bit feedforward sigma-delta modulator topology is chosen to meet both GSM and WCDMA specifications without needing additional hardware. Simulation results indicate that, 92-dB peak SNR is achievable over a 200kHz bandwidth, in GSM mode and 61-dB peak SNR over a 2MHz bandwidth, in WCDMA mode.
Keywords :
cellular radio; code division multiple access; radio receivers; sigma-delta modulation; telecommunication standards; 61 dB; 92 dB; GSM specification; GSM/WCDMA receivers; WCDMA specification; dual-mode receiver; feedforward sigma-delta modulator topology; feedforward signal path; multibit sigma-delta modulator; multibit topology; multistandard receiver; operational amplifier nonlinearity effect; oversampling ratio; third-order sigma-delta modulator; Bandwidth; Circuit topology; Delta-sigma modulation; Dynamic range; Feedback; GSM; Multiaccess communication; Power dissipation; Switching circuits; Wideband; feedforward; multistandard receiver; sigma-delta modulator;
Conference_Titel :
Circuits and Systems, 2003 IEEE 46th Midwest Symposium on
Print_ISBN :
0-7803-8294-3
DOI :
10.1109/MWSCAS.2003.1562220
