Which Virtual Probing Method to Use?

 

Virtual probing lets you "probe" where a probe
can't reach, or compensate signals by deembedding
or simulating devices and channels.

A great feature of Teledyne LeCroy oscilloscopes is the ability to apply virtual probing to compensate an input signal, whether by deembedding fixtures from the signal path, or simulating a “missing” component. It is especially helpful in cases where the signal is difficult to probe at the ideal location, hence the concept of “virtual” probing.

For example, because the JEDEC electrical specifications are defined at the balls of the DDR DRAM, it is often necessary to use the virtual probing capabilities of the oscilloscope to get the best representations of DDR signals to be analyzed with DDR Debug Toolkit or QualiPHY compliance software.

Here, we’ll give an overview of the virtual probing methods that become available with the installation of the SDAIII-CompleteLinQ or VirtualProbe software options, and some guidance as to which method is best to use in which case. And although we’ll show examples drawn from DDR analysis, the benefits of virtual probing are by no means limited to DDR signals.

Making Sense of Probe Terminology

As oscilloscope users, we know that the probe is a critical element in getting signals from the device under test into the instrument. The ideal probe would have perfectly flat magnitude response and perfectly linear phase response across its entire frequency range. Unfortunately, that probe, though striven for by all oscilloscope manufacturers, does not exist.