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Abstract

A transmission termination circuit able to reduce transmission signal reflections and resultant data corruption such that a single network may selectively communicate data using either a voltage driven transceiver or a current driven transceiver. A 10BASE-T transceiver has differential voltage driven outputs. A first output is coupled to a first terminal of a primary winding of a transformer through a first resistor. A second output is coupled to a second terminal of the first primary winding through a second resistor. A 100BASE-TX transceiver has differential current driven outputs. A first output is coupled to a first terminal of a second primary winding of the transformer. A second output is coupled to a second terminal of the second primary winding. A resistive snubber comprising a resistor in series with a capacitor is coupled across the 100BASE-TX outputs. A twisted-pair network is coupled to a secondary winding of the transformer. When transmitting in 10BASE-T format, the resistive snubber suppresses voltage transients caused by a leakage inductance in series with the reflected 10BASE-T circuit. The snubber has a time constant which is large enough suppress transients during transmission by the 100BASE-TX circuit, but small enough to not interfere with transmission by the 10BASE-T transceiver. The snubber matches impedances of the 10BASE-T and the 100BASE-TX transceivers over a wide range of frequencies to prevent signal reflections.

First Claim