Nortel Networks Corporation

Plant Equipment Inc.

Jane He

Liguo Zhao

A PCB comprising two or more components, such as ICs, comprises drivers and receivers that facilitate communication of signals between the components. Signal terminations, such as series and AC terminations, are used to increase the integrity of signals transmitted between components. Advantageously, values of the terminations are determined using a computerized method comprising sequential adjustment of on-chip programmable resistors and/or capacitors on chips coupled to the PCB. Thus, the effect of various values of on-chip termination resistors and/or capacitors on signal integrity is actually tested on the PCB, rather than simulating using software, for example, in order to determine optimal termination values. Characteristics of on-chip programmable resistors and/or capacitors may be adjusted by writing values into registers of the corresponding chips. The termination testing may be performed at various temperature and humidity settings corresponding to expected use environments in order to observe signal integrity at specific use environments.

System and method for automation of hardware signal characterization and signal integrity verification

In order to probe digital signals within a Printed Circuit Board (PCB) a sensor apparatus is implemented adjacent to a signal trace. The sensor apparatus receives crosstalk signalling from the signal trace and is coupled to a probing node capable of being probed by a test apparatus. Hence, in essence, the signal trace itself can be probed via the sensor apparatus and the probing node. The probing node can be implemented on the same layer of the PCB as its corresponding sensor apparatus or on a different layer that is more convenient for probing purposes. Further, the sensor apparatus could be implemented on the same layer within the PCB as its corresponding signal trace or alternatively could be implemented on an adjacent layer that still allows the sensor apparatus to receive crosstalk signalling from the signal trace. With the use of the sensor apparatus in combination with the probing node, it is possible to achieve accurate measurements of signals traversing the signal trace without significantly affecting the signal integrity of the signals traversing the signal trace. This is especially important in high speed designs.

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Ottawa, Canada

Jane He