’Scope power integrity measurements: Keysight's probes claim peak performance

October 09, 2014 // By Graham Prophet
Keysight Technologies claims highest bandwidth and lowest noise for its oscilloscope probe for making power integrity measurements to characterise DC power railsL the Power-Rail Probe delivers the most accurate view of DC power-rail behaviour up to 2 GHz

The N7020A power-rail probe specifications are tailored for a wide variety of DC power-rail measurements. Probe specifications include very low noise, a large ± 24-V offset range and 2-GHz bandwidth.

Successive generations of products have decreasing DC operating voltages as a way to reduce power and increase clock and data speeds. As DC power rails have shrunk in size, so have the tolerances on those power rails. One of the biggest sources of clock and data jitter in a digital system is noise on the DC power supplies. Development teams in almost all electronic industries measure the integrity of DC power rails and need tools that provide the signal detail associated with smaller and smaller DC voltages—often just a few millivolts.

The single-ended Keysight N7020A power-rail probe has a 1:1 attenuation ratio to maximise the signal-to-noise ratio of the power rail being observed by the oscilloscope. Comparable oscilloscope power integrity measurement solutions have up to 16x more noise than the Keysight solution, the company says. With its lower noise, the Keysight N7020A power-rail probe provides a more accurate view of the actual ripple and noise riding on DC power rails.

With its ± 24-V offset range, the N7020A power-rail probe has up 15 times more offset range than comparable power integrity measurement solutions. This large offset range allows engineers and technicians to centre their DC power rails on the oscilloscope screen and zoom-in on it for analysis.

The probe has a DC input impedance of 50 kΩ to minimize DC loading of the power rail when the probe is connected. Many comparable oscilloscope power integrity measurement solutions have a DC input impedance of only 50Ω, which can adversely affect the behaviour of the DC power rail.

The 2-GHz bandwidth allows analysis of fast transients on DC power-rails that can be detrimental to clocks and data. The N7020A offers up to four times more bandwidth than comparable oscilloscope power integrity measurement