If you're looking for a thorough validation of your e-MMC2 or UFS3 device designs before moving to mass production, consider performing a signal integrity (SI) analysis. Why is this important? As managed flash devices communicate in our fast-paced digital world, unwanted guests like parasitic effects4 and signal reflections5 can show up, causing communication errors. For high-speed UFS devices, an even more meticulous SI analysis is required to ensure that eye patterns6 are healthy, keeping those communication errors at bay.
Prior to conducting any measurements, you’ll need a high-speed oscilloscope and differential probes. If you’re measuring UFS 4.0 or UFS 4.1 devices, prepare to handle data transfer speeds up to 23.2 gigabits per second. These transfer speeds need an oscilloscope that can keep up! A good rule of thumb is to use equipment capable of handling at least 5x the maximum bandwidth of your device’s highest frequency to ensure that you capture all those critical signal harmonics. Also, make sure your PCB is clean with the soldering spot on to avoid any shorts or inconsistent connections. Everything must be perfectly mated. For e-MMC devices, consider adding a discrete pull-up on the CMD and DAT0 signals to help prevent data mishaps.
Once the equipment is hooked up, fire up that oscilloscope, configure it for your device specifications, and start capturing those signals. To best conduct the SI measurements, follow the JEDEC® standards closely, as presented in the table below, as they will guide you on what signals to measure and how to measure them.
It should also be noted that since UFS devices operate at higher frequencies and have limited test point access versus e-MMC devices, using an interposer board can help manage parasitic capacitance and signal reflections than can cause added impedance and incorrect readings.
Remember, the goal of the SI analysis is to validate your managed flash device design thoroughly before it goes to mass production. Accurate SI measurements are non-negotiable, as they are the backbone for ensuring that your device performs as expected in the real world, so preparation is key and having the right tools and setup will make all the difference.
Need some help? If you’re unsure about which JEDEC specifications to use, how to measure the device or need specific advice, don’t hesitate to reach out to the KIOXIA America, Inc. sales team who can provide guidance. Additionally, a tech brief on this subject is available here.
FOOTNOTES:
1 A managed flash device combines raw NAND flash memory and an intelligent controller in one integrated package, enabling internal memory management.
2 Embedded MultiMediaCard (e-MMC) is a specification developed by JEDEC® for mobile applications. The current release is v5.1, published in February 2015.
3 Universal Flash Storage (UFS) devices are based on the UFS specification, of which, the v4.1 specification is the current release issued by JEDEC and announced in January 2025.
4 Parasitic effects in integrated circuits (ICs) refer to unintended electrical characteristics and behaviors that arise due to the physical structure and layout of the circuit. These effects can impact resistance, capacitance, inductance and signal integrity.
5 Signal reflections in ICs refer to the phenomenon where a portion of an electrical signal is bounced back towards its source due to impedance mismatches or discontinues along the transmission line. These reflections can distort signals causing signal integrity issues.
6 Eye mask testing used in serial bus applications provides an eye diagram of all bits captured by an oscilloscope to show when bits are valid and a quick way to assess the quality of a serial signal.
TRADEMARKS:
JEDEC is a registered trademark of the Joint Electron Device Engineering Council (JEDEC) Solid State Technology Association. All other company names, product names and service names may be trademarks of third-party companies.
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KIOXIA America, Inc. All rights reserved. Information in this tech brief, including product specifications, tested content, and assessments are current and believed to be accurate as of the publication date of the document, but is subject to change without prior notice. Technical and application information contained here is subject to the most recent applicable KIOXIA product specifications. This technical brief is for informational purposes only and KIOXIA makes no representation or warranties of any kind, expressed or implied. Images within are for illustration purposes only.