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A new IQ detection method for LLRF

Qiu, Feng; Gao, Jie; Lin, Hai-ying; Liu, Rong; Ma, Xin-peng; Sha, Peng; Sun, Yi; Wang, Guang-wei; Wang, Qun-yao and Xu, Bo, et al. (2012) In Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment 675. p.139-143
Abstract
Digital LLRF technology has been widely used in new generation particle accelerators. IF quadrature sampling is a common method for amplitude and phase detection. Many strategies, which obey the same rule of f(sample) = (M/N)f(IF) (M/N is a rational number), have been proposed to reduce the effects of spectrum aliasing. However, we found that M/N does not need to be a rational number according to Shannon's theorem. Therefore, we propose a new IQ detection method in this paper. This method is based on a special IIR filter which is derived from an RLC circuit. The unique characteristic of the method is that the value of f(IF) is independent of the value of, f(sample). We have set up an experimental platform to verify our method. A 122.88 MHz... (More)
Digital LLRF technology has been widely used in new generation particle accelerators. IF quadrature sampling is a common method for amplitude and phase detection. Many strategies, which obey the same rule of f(sample) = (M/N)f(IF) (M/N is a rational number), have been proposed to reduce the effects of spectrum aliasing. However, we found that M/N does not need to be a rational number according to Shannon's theorem. Therefore, we propose a new IQ detection method in this paper. This method is based on a special IIR filter which is derived from an RLC circuit. The unique characteristic of the method is that the value of f(IF) is independent of the value of, f(sample). We have set up an experimental platform to verify our method. A 122.88 MHz sampling clock is used to sample a 3 MHz IF signal. The DOS and PI control techniques are used to realize the closed-loop control. Results show that the stability of the system is within +/- 0.05% (peak to peak) for the amplitude, and with +/- 0.03 degrees (peak to peak) for the phase in 5 h. (C) 2012 Elsevier B.V. All rights reserved. (Less)
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publication status
published
subject
keywords
LLRF, IQ detection, IIR filter, RLC circuit, DDS
in
Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment
volume
675
pages
139 - 143
publisher
Elsevier
external identifiers
  • wos:000302973600021
  • scopus:84862824418
ISSN
0167-5087
DOI
10.1016/j.nima.2012.01.068
language
English
LU publication?
yes
id
e5d6870a-a4bb-43a8-8349-232ebe17a2f3 (old id 2562985)
date added to LUP
2012-06-01 12:30:10
date last changed
2017-03-26 04:02:50
@article{e5d6870a-a4bb-43a8-8349-232ebe17a2f3,
  abstract     = {Digital LLRF technology has been widely used in new generation particle accelerators. IF quadrature sampling is a common method for amplitude and phase detection. Many strategies, which obey the same rule of f(sample) = (M/N)f(IF) (M/N is a rational number), have been proposed to reduce the effects of spectrum aliasing. However, we found that M/N does not need to be a rational number according to Shannon's theorem. Therefore, we propose a new IQ detection method in this paper. This method is based on a special IIR filter which is derived from an RLC circuit. The unique characteristic of the method is that the value of f(IF) is independent of the value of, f(sample). We have set up an experimental platform to verify our method. A 122.88 MHz sampling clock is used to sample a 3 MHz IF signal. The DOS and PI control techniques are used to realize the closed-loop control. Results show that the stability of the system is within +/- 0.05% (peak to peak) for the amplitude, and with +/- 0.03 degrees (peak to peak) for the phase in 5 h. (C) 2012 Elsevier B.V. All rights reserved.},
  author       = {Qiu, Feng and Gao, Jie and Lin, Hai-ying and Liu, Rong and Ma, Xin-peng and Sha, Peng and Sun, Yi and Wang, Guang-wei and Wang, Qun-yao and Xu, Bo and Zeng, Rihua},
  issn         = {0167-5087},
  keyword      = {LLRF,IQ detection,IIR filter,RLC circuit,DDS},
  language     = {eng},
  pages        = {139--143},
  publisher    = {Elsevier},
  series       = {Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment},
  title        = {A new IQ detection method for LLRF},
  url          = {http://dx.doi.org/10.1016/j.nima.2012.01.068},
  volume       = {675},
  year         = {2012},
}