M.~Wendt,
   "Direct (Under)Sampling vs Analog Downconversion for BPM Electronics",
   in Proc. 3rd International Beam Instrumentation Conference, Monterey, CA, USA, paper WEIYB1, pp. 486–494,
    ISBN: 978-3-95450-141-0,
    \url{http://jacow.org/IBIC2014/papers/weiyb1.pdf},
    2014.