Modern electronic products operate at higher frequencies, have increased functionality, and have densely populated PCBs. On effect thereof are lower supply voltages, commonly 3.3, 1.8, 1.5 and even 1.1 V DC. All these DC voltages have tighter tolerance compared to previous product generations.

Such dense PCBs with more functionality and higher frequencies are more susceptible to coupling and crosstalk leading to unwanted signal contents in the DC power rails. Even more, transients and ripple on DC power rails can also affect signal and clock lines, leading to power supply induced jitter.

Today’s engineers need to have the right tools at hand to analyze such phenomena and make well informed decisions on what kind of improvements of the hardware design have what kind of impacts on the signal quality.

The Keysight D9010POWA Power Integrity Analysis Application [download datasheet (PDF)], running for example on the industry leading Keysight MXR Oscilloscope family [learn more], provides exactly what is needed to perform power integrity analysis and make well informed decisions.

The following screen capture shows in the yellow trace a serial data signal and in blue, captured with a N7020A power rail probe, a 1.1 V DC power rail. The lower portion depicts the eye diagram of this serial data stream with an eye width of roughly 73 ps.

Power Integrity Fig 1

Modifying the circuit to get rid of the noise in the 1.1 V DC power supply has a tremendous impact on the eye width. This can be seen in the following picture, where the same serial data stream is used to generate a new eye diagram:

Power Integrity Fig 2

The eye width increased by almost 50 % to 114 ps, indicating that the noise on the 1.1 V DC power supply caused a substantial part of power supply injected jitter in the serial data line.

However, it is not guaranteed that a closed eye can be re-opened by fixing a noisy power supply. Therefore, it would be convenient if the application on the oscilloscope would be able to tell the user, if a clean power supply influences the eye opening of a serial data stream.

The D9010POWA Power Integrity analysis application can do exactly that. It predicts how the eye would look like if the adverse effects of the 1.1 V DC power supply were removed from the serial data. In the next picture, the upper eye diagram shows the eye diagram of the serial data with noisy power supply. The lower eye diagram is the simulation result without the adverse effects of the power supply corresponding to a clean 1.1 DC power supply. Comparing the measurement results from the simulated eye and the eye from the previous picture with the fixed power supply shows an almost perfect match between hardware fix and simulation.

Power Integrity Fig 3

Such simulation capabilities allow to make well informed decisions on what kind of hardware improvements are worth to invest in without the need of trial and error.

Such kind of handy tools greatly improve your time to market, increase the efficiency and provide you the insights you need. Right on the spot.

For further information, please contact our experts - we are happy to help you with your request!

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Christoph Zysset

Written by Christoph Zysset

Application engineer at Computer Controls AG, PhD from ETH Zürich