1-bit Band-Pass Delta-Sigma Modulator with Parallel IIR Form for Concurrent Multiband Digital Transmitter

Takashi MAEHATA  Suguru KAMEDA  Noriharu SUEMATSU  

Publication
IEICE TRANSACTIONS on Communications   Vol.E100-B   No.7   pp.1152-1159
Publication Date: 2017/07/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2016EBP3318
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
Keyword: 
bandpass,  delta-sigma modulator,  concurrent multiband,  D/A converter,  

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Summary: 
We propose an architecture for a 1-bit band-pass delta-sigma modulator (BP-DSM) that outputs concurrent multiband RF signals. The proposed BP-DSM consists of parallel bandpass filters (BPFs) in the feedback loop to suppress the quantization noise at each target frequency band while maintaining the stability. Each BPF is based on second-order parallel infinite impulse response (IIR) filters. This architecture can unify and reconfigure the split BPFs according to the number of bands. The architecture complexity is proportional to the bandwidth of each RF signal and is independent of the carrier spacing between the bands. The conventional architecture of a concurrent multiband digital modulator, reported previously, has multiple input ports to the dedicated BPF at each band and so it cannot be efficiently integrated. Measurements show that the proposed architecture is feasible for transmitting a concurrent dual-band and a triple-band by changing the 1-bit digital data stream while keeping a data transmission rate of 10Gb/s. We demonstrate that the proposed architecture outputs the signal with LTE intra-band and inter-band carrier aggregation on 0.8GHz, 2.1GHz and 3.5GHz, each with 40MHz bandwidth in 120MHz aggregated bandwidth, whose bandwidth surpasses the bandwidth with carrier aggregation of LTE-A up to 100MHz. Adjacent channel leakage ratios of -49dBc and -46dBc are achieved at 3.5GHz in the concurrent dual-band and triple-band, respectively.