Limit characteristics of the dc SQUIDS using unshunted Josephson tunnel junctions

A limit energy sensitivity is found for dc SQUIDS using unshunted Josephson tunnel junctions. Expressions are derived for the signal transfer function and for the voltage noise spectrum density in these devices. An analytical expression for the phase as a function of time has also been found in switching from zero to the voltage state process. The comparison is performed between these devices and usual dc SQUIDS using shunted Josephson tunnel junctions.