An Electronic Module for 12.8 Gbps Multiplexing and Loopback Test

A 2-channel module for testing serial and parallel signals up to 12.8 Gbps is described. It is intended to extend the capabilities of an existing 6.4 Gbps ATE, serving as a plug-in module in an active device interface board (DIB). This prototype circuit provides (1) direct connections to ATE channels for DC parametrics and low-speed functional testing, (2) 2:1 multiplexing of 6.4 Gbps to produce 12.8 Gbps stimuli with picosecond deskew, jitter-injection, and amplitude adjustment, (3) 1:2 fanout of 12.8 Gbps DUT response signals to allow testing by two 6.4 Gbps ATE channels, (4) full-rate low-jitter active loopback path with amplitude adjustment, and (5) auxiliary outputs for parallel monitoring of both transmitted and received signals. The basic logical structure is presented, and features of the module construction are described. A novel high-bandwidth adjustable delay circuit is described, that is used for deskew and XOR-based multiplexing. The performance of the module is demonstrated between 5.0 Gbps and 12.8 Gbps.