以太网 PHY 芯片技术白皮书

产品特点

连接MAC和物理介质（铜线/光纤），保证网络传输稳定
1. 信号调理
将MAC层发送的并行数据转换为串行比特流，并对接收到的模拟信号进行采样解码，将其恢复为数字信号；

2. 数据编码/解码
补偿高频信号在长距离电缆中的衰减，消除码间干扰（ISI），恢复信号波形；

3. 物理媒体接口
双绞线+光纤+背板；内置ESD保护和共模抑制；

4. 电源管理与诊断
Close unused transceiver channels when idle, and power consumption can be reduced by 70% in low-power mode; It has the function of detecting cable open circuit/short circuit/impedance abnormality and reading link status;

5. 链路协商适应速率
通过FLP（Fast Link Pulse）与对端设备协商最佳速率（10/100/1000Mbps）并快速建立重连；

信号调节/数据编码和解码

1.信号调理的必要性
·Signal amplitude adjustment: signal amplification for easy collection;·Improve signal-to-noise ratio: remove noise interference of electrical signals;·Signal conversion: realize signal conversion through functional relationship, which is convenient for observing required parameters;·Meet equipment requirements: signal matching;·Achieve long-distance transmission: anti-interference during long-distance transmission;·Protect equipment: protect back-end equipment when measuring high-voltage signals;

2.信号调理流程（适用于大部分长-距离通信）
信号放大->滤波->信号转换->线性化->隔离保护->调制解调->电平调整；


结构图

物理层芯片
PHY（Physical Layer）芯片是物理层的核心部件，负责发送和接收以太网信号。主要功能包括：
• 信号转换：将数字信号转换为适合网线传输的模拟信号（发送），将模拟信号转换为数字信号（接收）。
• Electrical protection: provide additional electrical isolation through the network transformer to protect the PHY chip from damage by external factors such as lightning strikes and electromagnetic interference.

网络变压器
• 信号耦合与传输：将PHY芯片输出的差分信号通过差模耦合增强传输到网线的另一端。
• 电气隔离：隔离PHY芯片与网线之间的直流电平差，防止不同设备之间的电压差损坏设备。
• 阻抗匹配：确保信号源、负载和传输线之间的阻抗匹配，以减少信号反射和误码。
• 电磁干扰抑制：抑制共模噪声，通过共模扼流圈（CMC）减少电磁干扰。


The above three parts are not necessarily all independent chips. There are mainly the following situations: MAC and PHY are integrated inside the CPU, which is more difficult; MAC is integrated inside the CPU, and PHY uses independent chips (mainstream solution); MAC and PHY are not integrated in the CPU, and MAC and PHY use independent chips or integrated chips (high-end use);




参数

1. 费率支持
• 支持的速率范围：PHY芯片需要支持目标应用所需的以太网速率，如10 Mbps、100 Mbps、1 Gbps、10 Gbps等；
• Adaptive rate negotiation: Support auto-negotiation function, which can automatically select the best rate (such as 10/100/1000 Mbps) and duplex mode (full-duplex/half-duplex) according to the capabilities of the peer device.

2、接口标准
PHY芯片需要与上层MAC层兼容。常见的接口包括：
• MII：适用于10/100 Mbps 以太网。
• RMII：MII 的简化版本，引脚较少，适用于 10/100 Mbps。
• GMII：支持1 Gbps 速率。
• RGMII：GMII 的简化版本，引脚较少，适用于 1 Gbps。
• SGMII：串行接口，适用于针数较少的1 Gbps。
• 物理介质接口（MDI）：支持的物理介质类型，如双绞线（BASE-T）、光纤（BASE-X）、单双绞线（BASE-T1）等。

3、传输距离
• Transmission distance: select a PHY chip that supports the required transmission distance according to application requirements. For example, 1000BASE-T (Gigabit Ethernet) supports twisted pair transmission up to 100 meters, while fiber PHY (such as 1000BASE-LX) can support longer distances.

4、功耗
• Power consumption level: low power design is critical for energy saving and heat management, especially in high-density devices (such as switches) and mobile devices. For example, a PHY chip that supports the EEE (Energy Efficient Ethernet) standard can reduce power consumption when idle.
• 热设计：考虑PHY芯片的散热要求，特别是在高温环境或高密度应用中。

5. 可靠、稳定
• Electrical isolation: electrical isolation is achieved through a network transformer to protect the PHY chip from damage by external factors such as lightning strikes and electromagnetic interference.
• Anti-interference capability: PHY chips should have good electromagnetic compatibility (EMC) and be able to withstand electromagnetic interference in industrial environments. For example, they should comply with standards such as CISPR 32 and IEC 61000-4-2.
• 工作温度范围：工业级PHY芯片通常支持较宽的温度范围（如-40°C85°C）以适应恶劣的环境。

6.特殊功能
• PoE 支持：如果应用需要通过以太网电缆供电（例如IP 摄像机、无线接入点），则需要选择支持PoE（IEEE 80
• Diagnostic function: Supports functions such as link status detection and signal quality monitoring to facilitate network maintenance and troubleshooting. • Security features: In some applications, PHY chips may need to support security features, such as encrypted communication or authentication functions.

应用场景


(1) 10/100Mbps 物理层
应用场景： 工业控制：PLC、传感器网络（如 Modbus TCP） 智能家居：智能插座、低功耗物联网设备（如 Zigbee 网关） 板载诊断：OBD-II 接口（100BASE-T1）

(2) 1Gbps 物理层
应用场景： 消费电子：4K电视、NAS存储 工业相机：机器视觉（实时图像传输） 企业网络：千兆交换机、路由器

(3) 2.5G/5G PHY（多-千兆位）
应用场景： 工业控制：PLC、传感器网络（如 Modbus TCP） 智能家居：智能插座、低功耗物联网设备（如 Zigbee 网关） 板载诊断：OBD-II 接口（100BASE-T1）

(4) 10G/25G 物理层
应用场景： 数据中心：服务器互联（SFP+/QSFP28） 5G基站：前传网络（eCPRI over 25G） 超高清视频制作：8K视频实时传输

(5) 40G/100G及以上PHY
Application scenarios: AI/supercomputing clusters: GPU/TPU interconnection (InfiniBand replacement) Core backbone network: metropolitan area network/inter-data center interconnection Optical communication: CPRI/OBSAI fiber fronthaul

设计选择

(1)MII（媒体独立接口）
Rate: 10/100Mbps Number of pins: 16+ Application scenarios: Early embedded systems (such as ARM9 industrial control boards) Low-complexity design (external MAC controller required) Disadvantages: Complex wiring, gradually replaced by RMII

(2) RMII（简化的MII）
Rate: 10/100Mbps Number of pins: 6 (data + clock) Application scenarios: Cost-sensitive devices (such as home routers) Space-constrained design (IoT modules) Advantages: Simplified wiring, support 50MHz clock

(3) RGMII（简化千兆位MII）
Rate: 1Gbps Number of pins: 12 (dual-edge sampling) Application scenarios: Gigabit switches, industrial gateways need to be compatible with 100M/1G flexible design Key points: Strict timing control is required (±1ns deviation tolerance)

(4) SGMII（串行千兆位MII）

Rate: 1G/2.5GbpsNumber of pins: 2 (differential pairs)Application scenarios: long-distance board-to-board connection (via SerDes)High-speed communication between FPGA and PHYAdvantages: strong anti-interference, support backplane transmission

(5)USXGMII(超高速MII)

速率：10Gbps 引脚数量：4（差分对）应用场景：多速率交换机（10M/100M/1G/10G自适应）数据中心leaf-spine架构特点：需要低抖动时钟（<0.5ps RMS）


优势
可按需定制合适的可靠性策略
产品的可靠性测试严格遵循以下国际标准：

建筑工程委员会（汽车电子委员会)

 联合电子设备工程委员会（联合电子器件工程委员会）

MIL（军用标准）

IEC（国际电工委员会）
为充分保证产品质量，我们从以下五个方面保证产品的可靠性：
工艺可靠性
封装工艺可靠性
产品可靠性
量产可靠性监控
故障分析