  We have fabricated and investigated a stacked two-chip device, consisting of
a lumped element resonator on one chip, which is side-coupled to a coplanar
waveguide transmission line on a second chip. We present a full model to
predict the behavior of the device dependent on the position of the lumped
element resonator with respect to the transmission line. We identify different
regimes, in which the device can be operated. One of them can be used to tune
the coupling between the two subsystems. Another regime enables frequency
tunability of the device, without leaving the over-coupled limit for internal
quality factors of about $10^4$, while in the last regime the resonator
properties are insensitive against small variations of the position. Finally,
we have measured the transmission characteristics of the resonator for
different positions, demonstrating a good agreement with the model.
