Speeding Edge, specialists in gigabit and higher designs, now offers test laboratory services for high-speed PCB impedance and power subsystem testing.
Two important tests that need to be performed
In order to ensure viability of the design in terms of high speed criteria, the following tests must be performed:
The expertise of Speeding Edge staff as well as equipment owned by the company enables the verification of transmission line impedances as well as the ability to test power supply impedance vs. frequency to support load requirements.
- Verifying that transmission line impedances are correct
- Testing the power supply impedance vs. frequency to make sure that all loads are properly supported.
Because the two pieces of equipment required to perform these tests-a time domain reflectometer (TDR) and a spectrum analyzer cost about $30,000 or more and are used infrequently, it does not make sense for most engineering departments to make these costly investments. In addition, the successful completion of these tests requires a specialized skillset not available in most departments.
Speeding Edge uses a TDR to measure transmission line impedance. The TDR consists of a voltage step generator that launches very fast rise time pulses down the line to be tested and a sampling oscilloscope that monitors the voltage that travels on the transmission line. From the size and polarity of a reflection, the transmission line impedance can be measured.
In addition, Speeding Edge maintains a spectrum analyzer that is used with a tracking signal generator to measure the impedance vs. frequency of a power subsystem. Both of the tests that Speeding Edge offers, verification of transmission line impedance and testing of power subsystem impedance vs. frequency, are offered as contract services and can be performed either at a customer facility or at the Speeding Edge headquarters.
Note: Performing both impedance and power supply tests is best done with special test structures designed into each PCB. Descriptions of these preferred test structures can be obtained from Speeding Edge.