Situational Awareness: The Impact of the Interconnect

Fig 1. Coaxial cable has little effect on signal rise time,
but that's not true for every connection method.

How you connect a signal to your oscilloscope affects your measurements, and knowing the impact of different connection methods is an important part of your situational awareness.  

Using the same 40 ps fast edge signal we used for the risetime measurements in the last post, we’ll compare connections made using coaxial cable and a 10x passive probe, with and without different accessories.

More on Quiet-Low I/O Drivers and Ground Bounce

Figure 1: To configure an I/O driver as a quiet-low line, its
output is connected directly to Vss on the die

Ground bounce can plague digital I/O lines with bit errors and turn your hair grey trying to uncover the cause in the process. But there is a trick you can use to make the analysis a little easier: using a quiet-low I/O driver as a sense line to reveal the existence, and magnitude, of ground bounce in your system.

DDR Memory Testing Part III: What Not to Do

Figure 1: Damping resistors on
solder-in probe tips

Testing of dual data-rate memory (DDR) devices and/or modules calls for careful application of some best practices for probing. There will also be cases where the use of chip interposers is called for. Heeding the advice provided in earlier Test Happens posts on this topic will go a long way toward successful probing and testing.

Back to Basics: Probes (Part II)

In a previous post, we provided some basic information about oscilloscope probes, including a brief survey of the different types and what can happen when the probe is connected to a DUT. In this installment, let's continue along those lines and take a closer look at passive probes.