Xilinx's FPGA families have evolved significantly over time, with each new series offering enhanced performance, features, and power efficiency to address the growing demands of various industries. Two of the most notable FPGA families from Xilinx are the 7 Series and the UltraScale Series. While both families are designed to provide programmable logic solutions for a wide range of applications, there are several key differences between them in terms of architecture, performance, features, power consumption, and use cases.
In this comparison, we will highlight the main differences between the Xilinx 7 Series FPGAs (Artix-7, Kintex-7, Virtex-7, and Zynq-7000) and the UltraScale FPGAs (Artix UltraScale, Kintex UltraScale, Virtex UltraScale, and ZCU UltraScale+).
1. Process Technology
7 Series FPGAs:
- Process Node: Built on a 28nm process technology (using TSMC’s 28nm HPL process).
- The 28nm process allows the 7 Series to balance performance, power, and cost-effectiveness for a broad range of applications.
UltraScale FPGAs:
- Process Node: Built on a more advanced 16nm FinFET process technology (using TSMC’s 16nm FinFET process for UltraScale and 16nm/14nm for UltraScale+).
- The use of the smaller 16nm process allows for significantly improved power efficiency and performance, with higher logic density and faster clock speeds compared to the 28nm process used in the 7 Series.
Key Difference:
- The UltraScale Series is based on a more advanced 16nm process, offering improved performance, power efficiency, and logic density compared to the 28nm process used in the 7 Series.
2. Performance and Logic Density
7 Series FPGAs:
- Logic Density: The largest devices in the 7 Series, such as the Virtex-7, can accommodate up to approximately 2 million logic cells, while Artix-7 devices start at around 15,000 logic cells.
- Speed: The performance is sufficient for high-bandwidth applications, with clock speeds of up to 500 MHz or more, depending on the model.
UltraScale FPGAs:
- Logic Density: UltraScale devices can scale up to over 6 million logic cells in the largest Virtex UltraScale devices. The smaller models still provide significantly more logic cells than their 7 Series counterparts.
- Speed: The UltraScale architecture allows for significantly faster clock speeds, with some devices reaching over 1 GHz clock speeds, depending on the application. UltraScale FPGAs also have much improved signal integrity, enabling higher performance at higher frequencies.
Key Difference:
- UltraScale FPGAs offer much higher logic density and faster clock speeds (up to 1 GHz or more) compared to the 7 Series FPGAs.
3. Power Efficiency
7 Series FPGAs:
- While the 7 Series FPGAs are relatively power-efficient, they are not optimized to the same extent as the UltraScale family.
- Power consumption is generally lower than previous FPGA generations, but they are not as power-efficient as newer technologies.
UltraScale FPGAs:
- UltraScale architecture brings significant improvements in power efficiency, thanks to the 16nm FinFET process. These devices offer up to 50% less power consumption compared to the 7 Series for equivalent performance levels.
- UltraScale+ devices, based on an even more advanced 16nm/14nm process, offer even greater power efficiency, reducing total power consumption by up to 60% compared to previous generations.
Key Difference:
- The UltraScale FPGAs provide significantly better power efficiency, achieving up to 50-60% lower power consumption compared to the 7 Series FPGAs.
4. I/O and Transceivers
7 Series FPGAs:
- Transceivers: The 7 Series FPGAs offer high-speed transceivers, such as those found in the Virtex-7 family, with speeds up to 28.05 Gbps.
- I/O Performance: These FPGAs support a variety of I/O interfaces, including high-speed serial interfaces, but their maximum data rate and performance are lower compared to UltraScale FPGAs.
UltraScale FPGAs:
- Transceivers: UltraScale devices include advanced transceivers that support data rates up to 32.75 Gbps for Virtex UltraScale and even higher speeds (up to 58 Gbps) in some cases with the UltraScale+ family. These transceivers are also more power-efficient.
- I/O Performance: UltraScale devices support an even wider range of high-speed I/O interfaces, including PCIe Gen 3 (and 4 in UltraScale+), Ethernet, CPRI, and others. They also offer higher data rates with better signal integrity.
Key Difference:
- UltraScale FPGAs provide higher-speed transceivers (up to 58 Gbps) and improved I/O performance compared to the 7 Series FPGAs (up to 28.05 Gbps).
5. Memory and Bandwidth
7 Series FPGAs:
- Memory Support: The 7 Series FPGAs support DDR3 memory interfaces, offering good memory bandwidth for many applications. However, their memory interfaces are not as advanced as those in UltraScale.
- Bandwidth: The memory bandwidth is sufficient for most general-purpose applications but is limited when dealing with data-intensive or high-throughput systems.
UltraScale FPGAs:
- Memory Support: UltraScale FPGAs support DDR4 and LPDDR4 memory interfaces, offering significantly higher memory bandwidth compared to DDR3 used in the 7 Series. They also support High Bandwidth Memory (HBM) in some models, providing a dramatic increase in memory throughput.
- Bandwidth: With the use of faster memory interfaces and HBM, UltraScale FPGAs offer much higher memory bandwidth, which is critical for data-heavy applications like machine learning, video processing, and high-performance computing.
Key Difference:
- UltraScale FPGAs support DDR4, LPDDR4, and HBM memory, offering significantly higher memory bandwidth compared to the DDR3 memory supported by the 7 Series.
6. Architecture and Integration
7 Series FPGAs:
- Architecture: The 7 Series FPGAs use a traditional architecture with customizable logic fabric, DSP slices, and high-speed transceivers, but they do not have as many built-in integrated features.
- Integration: The Zynq-7000 series integrates an ARM Cortex-A9 processor with programmable logic, offering a system-on-chip (SoC) solution. However, the integration of ARM processors and FPGA fabric is less advanced than in UltraScale+ devices.
UltraScale FPGAs:
- Architecture: UltraScale devices incorporate an advanced architecture with additional features such as 64-bit ARM Cortex-A53 processors (in UltraScale+) and even more efficient programmable logic blocks.
- Integration: The UltraScale+ family includes more powerful integrated ARM processors (Cortex-A53 or A72), enhanced DSP blocks, and more efficient memory controllers, offering a more complete SoC solution. UltraScale+ devices also include integrated High Bandwidth Memory (HBM) in certain models for further performance enhancement.
Key Difference:
- The UltraScale FPGAs provide more advanced integration with powerful ARM processors (Cortex-A53, A72) and higher integration of specialized resources like HBM and advanced DSP blocks, compared to the 7 Series FPGAs.
7. Cost
7 Series FPGAs:
- The 7 Series FPGAs are more cost-effective compared to the UltraScale family, making them ideal for mid-range applications or where budget constraints are a concern.
- These devices provide a good balance of performance and cost, especially in applications that do not require the most advanced features or extreme performance.
UltraScale FPGAs:
- Due to the advanced technology, enhanced performance, and higher integration, UltraScale FPGAs are more expensive than the 7 Series devices.
- These devices are better suited for applications that require high performance, low power, and the latest FPGA features, but their cost can be prohibitive for more budget-conscious projects.
Key Difference:
- UltraScale FPGAs are generally more expensive due to their advanced features and performance, while 7 Series FPGAs are more cost-effective for applications that do not demand the latest technology.
Conclusion
In summary, Xilinx 7 Series FPGAs are optimized for applications requiring a balance between cost, performance, and power consumption. They are based on a 28nm process and provide sufficient performance for many general-purpose applications. On the other hand, Xilinx UltraScale FPGAs are built on a more advanced 16nm process and offer significantly higher performance, power efficiency, and memory bandwidth. UltraScale FPGAs also provide better.
