Adaptive Blocker Rejection Continuous-Time $Sigma Delta $ ADC for Mobile WiMAX Applications
Hyungseok Kim
Junghan Lee
Copani, T.
Bazarjani, S.
Kiaei, S.
Bakkaloglu, B.
Arizona State Univ., Tempe, AZ, USA;
This paper appears in: Solid-State Circuits, IEEE Journal of
Publication Date: Oct. 2009
Volume: 44,
Issue: 10
On page(s): 2766-2779
ISSN: 0018-9200
INSPEC Accession Number: 10880527
Digital Object Identifier: 10.1109/JSSC.2009.2028053
Current Version Published: 2009-09-22
Abstract
An adaptive blocker-rejection wideband continuous-time (CT) sigma-delta (SigmaDelta) analog-to-digital converter (ADC) is presented. An integrated blocker detector reconfigures the ADC loop architecture to avoid overloading in the presence of strong interferers, improving receiver channel selectivity and sensitivity without increasing its dynamic range (DR) requirements. The adaptive operation relaxes receiver baseband channel filtering requirements for a worldwide inter-operability for microwave access (WiMAX, IEEE 802.16e) receiver. The ADC achieves 71 dB of dynamic range (DR), 65 dB of peak SNDR and 68 dB of peak SNR over a 10 MHz signal bandwidth, consuming 18 mW from a 1.2 V supply. The ADC system reconfigures the loop filter topology within 51 mus, improving receiver selectivity without any transient impact on BER. In the blocker suppression mode, the ADC can withstand 30 dBc blocker at the adjacent channel, achieving - 22 dB error vector magnitude (EVM) with a 24 Mb/s 16-QAM signal. The IC is fabricated on a 130 nm 8-level metal, metal-insulator-metal (MIM) capacitor, CMOS technology, occupying 1.5 times 0.9 mm2 silicon area.
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