Differential amplifier with improved dynamic range

Claim 1

A differential amplifier comprising: first and second potential terminals between which a power source voltage is applied; detecting means, including first and second transistors whose emitters are coupled to each other and further including a constant current source connected between said first potential terminal and the junction of the emitters of said first and second transistors, for detecting a voltage difference between first and second voltage signals supplied to the base of said first and second transistors, respectively; amplifying means including third and fourth transistors which have a complementary relationship to said first and second transistors, and whose emitters are respectively connected to the collectors of said first and second transistors, said amplifying means also including a bias circuit for supplying bias voltages to the bases to said third and fourth transistors, and a load circuit connected between the collectors of said third and fourth transistors and said first potential terminal; first connecting means coupling said second potential terminal with the emitter of said third transistor, for setting the potential at the emitter of said third transistor to a level corresponding to that of said second potential terminal; and second connecting means coupling said second potential terminal with the emitter of said fourth transistor, for setting the potential at the emitter of said fourth transistor to a level corresponding to that of said second potential terminal.