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DDR6 RAM: Advantages and Challenges

Key Takeaways

  • DDR6 RAM is the latest among the DDR iterations and the maximum data rate peaks above 12000 MT/s.

  • The conductor and dielectric materials used in DDR6 memory interfaces influence signal integrity at high data rates. 

  • DDR6 design requirements include clean voltage supply, optimum working temperature, proper trace length matching, good termination, proper setup, and hold time to accomplish high signal integrity and power integrity in high-speed signal transmissions.

 RAM graphic

Double data rate (DDR) is the fastest technology available in RAM

Double data rate (DDR) is currently the fastest technology available in random access memory (RAM). DDR RAM technology has gone through many versions, and each version offers higher data rates and bandwidth than the previous version. DDR6 RAM is the latest DDR iteration, and it offers the maximum data rate peaks (above 12000 MT/s).

Unfortunately, the high-speed data flow and bus design of DDR poses challenges during the DDR PCB design process. These challenges are similar to the complications in high-speed PCB design. In this article, we will explore DDR6 RAM and discuss some common DDR6 RAM design challenges.   

DDR6 RAM

DDR6 is the next-generation RAM. It offers a high-speed memory design suitable to support applications requiring high memory bandwidth. DDR6 RAM was designed to achieve improved reliability, low latency, and high longevity compared to its predecessors. There is a specialist memory technology, GDDR6, that provides great bandwidth. The bandwidth feature of GDDR6 makes it the best candidate for graphics applications.

DDR6 and GDDR6 are ideal options as the demand for universal memory devices and enterprise storage applications increases. There will continue to be a huge market demand for DDR6 RAM due to its high bandwidth, low latency, and low power consumption. Technologies such as the Internet of Things (IoT), big data, and artificial intelligence (AI) will continue to use DDR technology. 

Due to exploding demand, DDR boards undergo a short design to market time. However, this hasty process can lead to issues. Designs using DDR6 typically become faulty due to complications in data, address, clocks, or control lines. We will dive into the challenges in DDR designs, and particularly in DDR6 designs, in the upcoming section.

Common DDR Design Challenges

Printed circuit board designs using DDR memory are challenging to create. DDR handles two data-bit transitions over the rising and falling edge of a single clock signal. DDR memory design challenges include chip-level and board-level challenges. The designers of DDR memory controllers face issues in IC designs due to complicated timing issues and high-speed signaling.

DDR memory devices use multi-level modulation such as PAM or QAM to boost the data rate above the fully analog channels. For DDR6 and higher generations, PAM or QAM modulation is usually coupled with equalization schemes. Employing multi-level modulation and equalization schemes requires careful DDR design. The use of different lines such as data, clock, address, and control along with mixed-signal aspects in the memory architecture requires the designer to polish their problem-solving skills to ensure a better layout design.

DDR memory interfaces need to satisfy power integrity as well as signal integrity requirements in the chip die, package, memory components, and board traces. When it comes to traces, the DDR memory configuration interfaced with multi-Gigabit transmission requires specific routing patterns. The high-speed performance of DDR memory gets better only by sorting out the challenges in routing, termination schemes, crosstalk interferences, impedance discontinuities, and timing margins. 

DDR6 RAM Design Challenges

In most applications, DDR6 RAM is going to rely on flip-chip ball grid array packaging for higher pin density and reduced power delivery. Usually, the controller and receiver in the DDR6 memory interface are laid on a PCB. There are chip-level and board-level design issues in DDR6 memory architecture. In this section, we will discuss some signal integrity failures in DDR6 memory bus designs. 

Signal Integrity Failures in DDR6 Memory Bus Designs

The conductor and dielectric material used in DDR6 memory interface designs influence the signal integrity at high data rates. The strength of the signal at the receiver end can be reduced due to the magnetic energy absorbed by the dielectric material from the signal lines. The length of the channel is a limitation to the signal integrity in DDR6 designs.

To improve power integrity and signal integrity, short channels or low-loss dielectric materials are needed. A phenomenon called the skin effect intensifies the signal insertion loss of multi-gigabit signal transmissions. The coupling of the energy between signals that are adjacent to each other in the package as well as in the board cause crosstalk interference in DDR memory interface designs.

The differences in the impedance along the signal path leading from the transmitter to the receiver in DDR6 memory architecture induce signal reflection losses and degrade the quality of the received signal. The impedance discontinuities are introduced by plated through-hole vias, micro vias, signal traces, BGA balls, or PCBs.

It is necessary to focus on certain design considerations to establish power and signal integrity in DDR6 memory architecture. DDR6 design requirements include clean voltage supply, optimum working temperature, proper trace length matching, good termination, proper setup, and hold time to achieve high signal integrity and power integrity in high-speed signal transmissions.

Cadence’s suite of design and analysis tools offers high-speed PCB design assistance for building the right DDR6 routing patterns. If you’re looking to learn more about how Cadence has the solution for you, talk to our team of experts.