What is the solution for power rail noise that causes system hangs?

As the transition from linear power supplies to switching power supplies and from silicon to WBG semiconductors (GaN·SiC) is rapidly progressing, power integrity is emerging as a key issue in power electronics design. Ho-Joong Lee, a representative of Keysight Technologies, presented a high-performance power measurement solution responding to this trend, emphasizing that “the era of precisely measuring and analyzing power quality has arrived.”

“In the past, there was a margin of about 5V ±10%, but recently, the margin has become extremely narrow, at the level of 1.8V ±1~3%. It is no exaggeration to say that even a small amount of noise can affect the reliability of the entire system.” (Keysight Technical Support Team Representative)

High-resolution measurements required for high-speed switching devices
As switching speeds increase from hundreds of kHz to several MHz, the bandwidth and resolution of measurement equipment are also new requirements. “Since WBG semiconductors have switching frequencies tens of times faster than silicon, the oscilloscope bandwidth for waveform capture and interpretation must also be sufficiently high,” said Lee.

For this purpose, Keysight proposes power rail-specific probes (N7020A, N7024A) that provide bandwidths of up to 2 GHz and an attenuation ratio of 1.1:1. In particular, the N7024A supports 6GHz bandwidth and a low noise floor, providing “over 67% noise reduction,” it said.

Current integrity, not just voltage, is also a must
Accurate current measurement is also essential. “Existing clamp-on probes basically contain noise of several mA, so they have limitations in measuring sleep current or low current,” said Lee. “High-sensitivity shunt-type probes such as the N2820A can accurately measure at least 100 nA,” he explained.

In addition, analysis of various parameters such as Ripple, Efficiency, PSRR, and SOA occurring in high-speed operating power supplies is also supported in a single oscilloscope software. “It is time to move beyond simple waveform viewing and expand measurement items with analysis software,” he explained.

Power quality must now be considered from the design stage
“In the past, power quality was a component-level issue, but now it is a key design requirement that determines the operational stability of the entire board,” said the representative. “Power rail measurement is not a simple test, but a task to secure reliability at the system level.”

“It is also essential to have the ability to remove noise generated during the measurement process or to compensate for environmental variables in the oscilloscope,” he said, adding that Keysight’s power integrity measurement software “enables accurate diagnosis even in complex power environments by including FFT analysis, mask testing, and digital compensation functions.”