  Microwave Kinetic Inductance Detectors (MKID) are a promising solution for
spaceborne mm-wave astronomy. To optimize their design and make them
insensitive to the ballistic phonons created by cosmic-ray interactions in the
substrate, the phonon propagation in silicon must be studied. A dedicated fast
readout electronics, using channelized Digital Down Conversion for monitoring
up to 12 MKIDs over a 100MHz bandwidth was developed. Thanks to the fast ADC
sampling and steep digital filtering, In-phase and Quadrature samples, having a
high dynamic range, are provided at ~2 Msps. This paper describes the technical
solution chosen and the results obtained.
