Advanced Micro Devices Corporation

Ravindra D Tembhekar

David L Campbell

Method and apparatus suitable for inclusion in an integrated circuit transceiver meeting IEEE 802.3 standards which detects 'collisions' so that more than one station will not simultaneously transmit over a network. The method employs a novel three-pole cyclical low-pass filter which attenuates the ac component received over the network to less than 20 mV to allow collision detection within the 900 nanosecond budget allowed by the IEEE standard. A differential operational amplifier receives the signal from the network and a collision reference voltage. The signal generated by the differential amplifier is filtered by the low-pass filter and then coupled to a high-gain comparator which acts as a zero-crossing detector. The comparator generates ECL logic signals representing the occurrence or non-occurrence of a collision. The resulting collision detector operates over a wide range without the need for field 'trimming'.

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Santa Clara, CA, United States of America

Ravindra D Tembhekar