  A common-mode free cavity BPM is currently under development at Fermilab
within the ILC-CLIC collaboration. This monitor will be operated in a CLIC Main
Linac multi-bunch regime, and needs to provide both, high spatial and time
resolution. We present the design concept, numerical analysis, investigation on
tolerances and error effects, as well as simulations on the signal response
applying a multi-bunch stimulus.
