Northern Telecom Limited

Dennis A Yarak

John Gordon Hogeboom

Arlan J Anderson

Terry N Thomas

High-speed bipolar signals transmitted along standard twisted pair telephone wiring are subject to InterSymbol Interference which is corrected by an equalizer circuit that is operably responsive to predetermined parameters of bipolar signals detected at the secondary of a line transformer. These parameters are input to a control logic circuit which includes several stages, each producing a set of past dependent logical control signals which are input to corresponding equalizer tap circuits having outputs connected to a common output bus. Each tap circuit includes an integrator that is incrementally charged and discharged by an electronically switched capacitor. A tap weight voltage output from each integrator is subsequently summed directly or inversely by a second switched capacitor under control of the logical input signals. And, an equalizing signal output from the second capacitor is coupled through a buffer amplifier to the line transformer where it is added to the incoming signal and allows eye diagram monitoring directly at the transformer.

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Palo Alto, CA, United States of America

Dennis A Yarak