  Recently a new explanation for the quantized current of the surface acoustic
wave (SAW)-driven single electron pumps was suggested [1]. In the SAW-driven
pumps the electrons are transported by the SAW along a one-dimensional
semiconductor channel. The suggested in ref.1 mechanism requires the presence
of a static quantum dot in the 1D channel and is qualitatively different from
that described in the original papers on single electron SAW-pumps. We have
analysed the available experimental data on the quantized current (including
the data presented in ref.1) and have come to the conclusion that the data can
not be explained by the mechanism suggested in ref.1. Moreover, we argue that
the data presented in ref.1 do not warrant the claim of the authors that a new
mechanism of the current quantization was observed.
