Negative resistance repeater

Claim 1

A negative impedance repeater arrangement for connection to communication lines comprising, coupling means arranged for connection to the communication lines to sense the impedance of the line in accordance with the signals passing over the communication lines, a series repeater connected to said coupling means, said series repeater including first operational amplifier means having first and second input terminals and a first single output terminal, said first and second input terminals being noninverting and inverting inputs respectively of said amplifier means with respect to said first single output terminal, said second input terminal being connected to said coupling means, a first feedback circuit connected between said first single output terminal and said first input terminal, said first feedback circuit including a series capacitor, a second feedback circuit connected between said first single output terminal and said second input terminal, the negative impedance sensed at said second input terminal being coupled into the communication lines by said coupling means, a shunt repeater connected to said coupling means, said shunt repeater including second operational amplifier means having third and fourth input terminals and a second single output terminal, said third and fourth input terminals being noninverting and inverting inputs respectively of said amplifier means with respect to said second output terminal, said fourth input terminal being coupled to said coupling means, a third feedback circuit connected between said second single output terminal and said third input terminal, said third feedback circuit including a series capacitor, and a fourth feedback circuit connected between said second single output terminal and said fourth input terminal, and transformer means associated with said fourth feedback circuit to transformer couple the negative impedance developed within said second single output terminal into said coupling means.