Electronic hybrid amplifier

Claim 2

A two wire transmission system having individual legs across the output of a transformer coupled to a balanced load, wherein AC signals received across the input of the transformer are inverted relative to one another in the respective legs; the invention comprising a first and a second difference amplifier, each having two input terminals and an output terminal, means coupling one input terminal of said first amplifier to one output leg of said transformer to receive signals therefrom, means coupling the other input terminal of said first amplifier to the other output leg of said transformer to receive inverted signals therefrom whereby to algebraically subtract in said first amplifier signals received from said transformer, and said second difference amplifier in said second leg with its output terminal coupled to the other leg of said transformer; the input terminals of said second amplifier coupled to the output of said first amplifier to attenuate signals reflected from the output of said first amplifier.

Claim 3

A two-wire transmission system as claimed in claim 1, wherein said first and second amplifiers comprise unidirectional circuits, and in which there are means biasing said circuits to provide the unidirectional bias.

Claim 4

A system as claimed in claim 2, wherein there are means biasing said difference amplifiers to unconditional stability during changes in impedance within the transmission system.

Claim 5

A transmission system as claimed in claim 1 wherein there is an impedance across the inputs to said second amplifier.

Claim 6

A bidirectional two-wire hybrid comprising a first and a second transformer across the respective inputs to said hybrid, each of said transformers having the input thereof balanced relative to ground, a first and a second path coupling the outputs of said transformers to one another, a first and a second operational amplifier each having two inputs, each amplifier being of the type which algebraically subtracts signals received over its two inputs, the inputs of said first amplifier being coupled across the outputs of said first transformer and the inputs of said second amplifier being coupled across the output of said second transformer, the output of said first transformer coupled to a said second transformer and comprising said first path, and the output of said second transformer being coupled to an output lead of said first transformer and comprising said second path, whereby signals received by either transformer are inverted relative to one another in the paths for amplification in the respective amplifiers, and reflected signals are attenuated within the respective amplifiers.

Claim 7

A bidirectional two-wire hybrid comprising a first and a second transformer across the respective inputs to said hybrid, each of said transformers having the input thereof balanced relative to ground, a first and a second path coupling the outputs of said transformers to one another, a first and a second operational amplifier each having two inputs, each amplifier being of the type which algebraically subtracts signals received over its two inputs, the inputs of said first amplifier being coupled across the outputs of said first transformer and the inputs of said second amplifier being coupled across the output of said second transformer, the output of said first transformer coupled to a said second transformer and comprising said first path, and the output of said second transformer being coupled to an output lead of said first transformer and comprising said second path, whereby signals received by either transformer are inverted relative to one another in the paths for amplification in the respective amplifiers, and reflected signals are attenuated within the respective amplifiers.

Claim 8

A hybrid circuit as claimed in claim 5, wherein said first amplifier comprises a transistor having an emitter terminal and a base terminal, with the output legs from said transformer coupled to the base and emitter of said transistor.

Claim 9

A hybrid circuit as claimed in claim 6, wherein said second amplifier comprises a transistor, having an emitter terminal and a base terminal and said other input circuit to said first amplifier transistor is connected to the base terminal of said second transistor, and the collector of said second transistor is connected to the base terminal of said first transistor.