A pair of terminals at which a signal may enter or leave a network is called a port The four-terminal network input output When i=i, and i,= a two-port network The two-port is composed of linear elements, including dependent sources but not containing any independent SourcesA pair of terminals at which a signal may enter or leave a network is called a port. The four-terminal network When i1=i1 ’ and i2=i2 ’ --a two-port network The two-port is composed of linear elements, including dependent sources but not containing any independent sources. 1 i i ' 1 2 i i ' 2 input output