Analysis: Examination of a Rapid Video Processing Circuit Layout
High-speed video boards, a critical component in various industries, are designed to facilitate seamless high-speed video transfer, processing, and display. One such board, designed by Sierra Circuits, stands out for its innovative design and robust specifications.
The board employs MIPI, a physical layer interfacing standard, to define interfaces among the physical layers and how devices communicate with each other. However, USB 3.0, a popular computer interface, is not explicitly mentioned as used in this specific board.
Despite the challenge posed by the board's density and the need to have connectors in specific places, the placement of components was carefully planned. This meticulous approach is crucial in maintaining signal integrity over high-speed serial interfaces such as PCIe, USB 3.x, HDMI, and SerDes.
Applications of High-Speed Video Boards
High-speed video boards find extensive use in several sectors. In professional video and camera systems, they enable 4K/8K video streaming with seamless data transfer for cameras and broadcasting equipment.
In the automotive industry, video boards support advanced driver assistance systems (ADAS), infotainment, and automotive cameras, relying on SerDes transceivers and high-speed interfaces.
Industrial automation and machine vision make use of these boards in image recognition, industrial vision, and smart devices for quality control and process monitoring.
Telecommunications and networking require high-speed video boards with fiber optic or Ethernet PHY transceivers for data centers, switches, and routers handling high data rates.
Medical imaging and military applications often demand high reliability and performance, with high-speed video boards often meeting IPC Class 3 standards for critical imaging and control systems.
Edge computing and AI-enabled smart devices, such as drones, robots, and cloud terminals, benefit from boards like RISC-V development platforms that provide 4K video processing combined with AI for intelligent applications.
Design Considerations
Sierra Circuits' design approach for high-speed video boards emphasizes high-frequency materials, HDI technology, multilayer layouts, precise impedance control, and rigorous reliability standards to meet these challenges effectively.
Material selection focuses on high-frequency/low-loss PCB materials to maintain signal integrity over high-speed serial interfaces. Multilayer PCB design is used to reduce noise, critical for high-speed differential pairs used by transceiver ICs.
HDI technology enables fine trace geometry and via-in-pad designs to minimize crosstalk and support gigabit speeds. Via types, such as microvias, blind and buried vias, and sequential lamination, are used to reduce signal path length, enhance thermal dissipation, and improve structural integrity for high data rates above 10 Gbps.
Impedance control and EMI management ensure clean video signal transmission at high frequencies, with tight impedance matching and reduced electromagnetic interference. Reliability standards are met by designing boards to meet IPC Class 3 standards, ensuring high quality, durability, and service in harsh environments.
The high-speed video board designed by Sierra Circuits is a 10-layer board of 9" x 3" (228.6 x 76.2 mm) size with 4 power layers and 6 signal layers. It is used in various sectors, including the automobile industry, healthcare, consumer electronics, and defense sector.
To address the design challenges, the PCB design team at Sierra Circuits used controlled impedance traces with length matching to around 50 mils to match the HDMI input signals. The board's irregular shape and specific form factor posed a challenge in the design process.
The board includes controlled impedance traces - 100 Ohms differential and 50 Ohms single-ended - which are critical for maintaining signal integrity. The serial-parallel interface (SPI) is used for routing between the traces and external devices or components. I2C, a protocol for controlling other devices' transmission line behavior, is also used in the board with controlled impedance.
In the automobile industry, high-speed video boards are used to facilitate navigation systems, control systems, and sensors in vehicles. In the healthcare industry, high-speed video boards are used in advanced medical equipment, diagnostics, and monitoring devices, with miniaturized cameras playing a vital role in diagnostics.
In the defense sector, high-speed video boards are used in strategic defense equipment like missiles, in monitoring, navigation, control, and communication systems. In consumer electronics, high-speed video boards are used to support high-resolution in devices ranging from computers to smartphones.
RF Bluetooth of 2.4 GHz was considered in this high-speed video board, which transmits signals over a shorter distance using high-quality radio waves. The memory interface implemented in the board is DDR3 with 800MHz, which has a high clock rate and large storage capacity.
In summary, high-speed video boards enable advanced video and imaging applications across professional video, automotive, industrial, medical, and networking sectors. Sierra Circuits’ design approach emphasizes high-frequency materials, HDI technology, multilayer layouts, precise impedance control, and rigorous reliability standards to meet these challenges effectively.
The high-speed video board designed by Sierra Circuits utilizes MIPI technology for defining interfaces and device communication, and it employs controlled impedance technology to maintain signal integrity. This controlled impedance technology is critical in maintaining the integrity of high-speed serial interfaces such as HDMI, USB 3.x, and SerDes, even with the board's density and the need for specific connector placements.
In the automobile industry, the use of high-speed video boards extends to navigation systems, control systems, sensors, and advanced driver assistance systems (ADAS) due to the reliance on Serializer-Deserializer (SerDes) transceivers and high-speed interfaces. In the board designed by Sierra Circuits, controlled impedance traces, including 100 Ohms differential and 50 Ohms single-ended, are utilized.
