Concept, realization and characterization of serially powered pixel   modules (Serial Powering)
  We prove and demonstrate here for the example of the large scale pixel detector of ATLAS that Serial Powering of pixel modules is a viable alternative and that has been devised and implemented for ATLAS pixel modules using dedicated on-chip voltage regulators and modified flex hybrids circuits. The equivalent of a pixel ladder consisting of six serially powered pixel modules with about 0.3Mpixels has been built and the performance with respect to noise and threshold stability and operation failures has been studied. We believe that Serial Powering in general will be necessary for future large scale tracking detectors. 
D.B. Ta, T. Stockmanns, F. Huegging, P. Fischer, J. Grosse-Knetter Oe.   Runolfsson, N. Wermes