Abstract: A token ring concentrator port circuit including an upstream data node, a downstream data node, a station receiver node, a station transmitter node, a path switch configured to selectively either connect the upstream data node directly to the downstream data node or connect the station receiver and transmitter nodes between the upstream and downstream data nodes, and a timing recovery circuit including a phase locked loop that derives a recovered clock from data from a station connected to the station receiver and transmitter nodes and reclocks the data with the recovered clock before transmitting the data to the downstream data node, the phase locked loop including a constant gain phase detector, the timing recovery circuit including a frequency limiting circuit, the port circuit components being implemented in a common integrated circuit.