GB1491885A - Active hybrid circuit - Google Patents

Abstract

1491885 Active hybrid circuits GENERAL ELECTRIC CO 28 Oct 1974 [29 Oct 1973] 46447/74 Heading H4R In an active hybrid circuit for connecting transmit and receive channels of a four wire line to a two wire line a first amplifier 24 is connected to receive a signal from the receive port 20 via a resistor 23, which terminates the receive channel in its characteristic impedance, and feeds its output to the two wire line via a fixed impedance 27, 28, which terminates the two wire line in its characteristic impedance while a second amplifier 31 has a first input which represents the signal derived from the receive channel and a second input which receives from the fixed impedance 27, 28 both the signal incoming from the two wire line and a phase inverted version of the signal at the first input so that the signal from the four wire receive channel is not present at the output of the second amplifier, which output feeds the transmit channel of the four wire line via a resistor 33 which terminates that line in its characteristic impedance. In a modification Fig. 3 (not shown) unity gain inverting amplifiers (34 and 37) provide balanced signals to the two wire and four wire lines and a differential amplifier receives balanced signals from the four wire receive channel. A more practical embodiment of the balanced arrangement of Fig. 3 is described with respect to Fig. 4 (not shown).