Cancelling Noise in Multi-Band Digital-Intensive Transmitters

    •  Chung, S., Ma, R., "Cancelling Noise in Multi-Band Digital-Intensive Transmitters", Asia-Pacific Microwave Conference (APMC), DOI: 10.23919/APMC.2018.8617217, November 2018.
      BibTeX TR2018-157 PDF
      • @inproceedings{Chung2018nov,
      • author = {Chung, Sungwon and Ma, Rui},
      • title = {Cancelling Noise in Multi-Band Digital-Intensive Transmitters},
      • booktitle = {Asia-Pacific Microwave Conference (APMC)},
      • year = 2018,
      • month = nov,
      • doi = {10.23919/APMC.2018.8617217},
      • url = {}
      • }
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  • Research Areas:

    Communications, Signal Processing

Digital-intensive RF transmitters using delta-sigma modulation have a compact physical footprint, enabling a low-cost mobile MIMO transmitter for 5G systems, but suffer from a high noise floor due to quantization errors. In order to eliminate the need of high-Q multi-band RF filters for attenuating such high noise floor, this paper for the first time presents a multi-band noise cancellation technique for digital-intensive transmitters based on concurrent multi-band delta-sigma modulation. Using an asymmetric RF power combiner, an experimental implementation realizes the bandpass noise cancellation for non-contiguous interband carrier aggregation of 835 MHz and 1450 MHz bands. For 40-MHz aggregated bandwidth, the proposed noise cancellation technique achieves ACPR better than -47 dB and -42 dB for the low-band and the high-band, respectively. With the dual-band prototype with a 6-GHz sampling rate, the proposed technique needs three times less bandwidth for noise cancellation signal compared to conventional feed-forward techniques, and thus the sampling rate requirement on noise cancellation path can be significantly relaxed.