Hybrid circuit with active components - has current source in balancing network which is controlled by four-wire incoming voltage

摘要

The two-wire line is isolated by a differential transformer. The hybrid circuit uses a four-wire input and a four-wire output. The balancing network consists of a current source controlled by the incoming four-wire voltage (Uan) through a network (ZT), and of a terminating impedance (Ra). The network (ZT) is between the input of the trlasformer secondary winding and the current source. The latter is between the differential transformer centre tapping and earth, and the terminating impedance (Ra) between the transformer secondary winding output and earth.