前Design Tips for the Automotive RF Front End

无线汽车复杂性蓬勃发展。这是如何解决它的。

谁能想象汽车生态系统的演变？曾经是一种简单的运输方式的形式变形为一个带有复杂的计算机系统的车辆，将自己和我们连接到世界各地。现在它驱动有点自动，与网络进行通信，并提供娱乐 - 而分析师预测这些趋势只会增长。根据麦肯锡公司，网络汽车数量将在未来几年增加30％;到2020年，五辆车将连接到互联网。Strategy Analyticspredicts the vehicle process and linear高级驾驶员辅助系统(ADAS) RF front-end (RFFE) market will be the largest, growing with a CAGR of 17% (2017-2022).

So how does an automotive RF engineer design a connected vehicle? Let’s first examine how to overcome some of the biggest RF challenges in automotive design.

Today’s automotive landscape: A complex ecosystem of standards and challenges

Today’s vehicles have a lot of electronics connecting it to the world. For RF systems, this means the RFFE chains abound as vehicle manufacturers place more telecommunications in the car. The following diagram shows an example of a generic system.

The changes in the automotive RF ecosystem bring several challenges for the RF system designer:

• 整合many standards into the vehicle and sometimes into one module
• Coexistence担心由于许多这些标准密切接近
• Minimizing electronic component热
• Higher level of concern forpower consumption,因为所有车辆设备都在相同的电池电源上工作
• 确保产品组件长期reliability

这些挑战并不是汽车行业的独有，克服它们的策略类似于其他应用程序，如Wi-Fi连接和移动设备。以下是在为汽车选择RF组件时的一些基本设计提示：

• 用highly linear active or front-end devices.
• 用components that minimize insertion loss in the RFFE and decrease the overall RF link budget.
• 请注意，目前效率，电流消耗和功耗。
• 使用高性能RF滤波器来最小化插入损耗，温度漂移和干扰。
• Consider using components that integrate transmit, receive and filter functions in a single package.
• 用汽车合格产品，坚持IATF和IEC行业标准。

让我们深入了解RF共存，集成，天线设计，热管理，电池寿命和车辆可靠性的设计考虑因素。

解决RF共存

用rs who are streaming video expect fast, reliable service in their automobiles, and streaming from the network and inside the vehicle are quickly becoming the standard. As a result, it’s important to minimize coexistence issues and reduce line loss when maintaining streaming services.

但最大化无线乐队和标准之间的共存是具有挑战性的。如果未使用适当的过滤，则以下频率下的共存问题可能增加：

Diagrams of the 2.4 GHz and 5 GHz spectrum show how crowded the bandwidths are for wireless technologies used in connected cars.

So, what’s the best way to mitigate these coexistence issues? Some best practices are to use high-performance RF filters and highly linear active devices in your design.

• Filters reduce the out-of-band interference between radio signals.
• Coexistence filters mitigate potential脱敏for transmitted signals.

今天的车辆通信支持天线和收发器之间的许多发射和接收路径，并且这些路径的隔离需要滤波器。这些过滤器必须：

车辆工程师曾经只关注GPS和蓝牙，但现在他们必须设计新的无线标准如C-V2Xand, in the future, 5G New Radio (NR). Designers must learn all the technology shown in the block diagram below, while incorporating it into their automobile designs. The most likely approach will use mobile phone technology as a springboard.

Qorvo工程师创建了rf fusion™to help our customers leverage an integrated solution, which effectively reduces design complexity and enables faster time to market. Many of these complex modules include embedded filters, which further reduce the RF complexity and the overall link budget.

天线和rffe

Picture a shark fin antenna that’s connected to a cable, which then runs to the low noise amplifier (LNA) elsewhere in the car (usually in the dashboard). While it’s common practice for cabling to be used in traditional vehicle manufacturing, lengthy cabling can cause insertion loss between the antenna and the RFFE (increasing the link budget). This also increases noise figure (NF) on the LNA input, especially in cellular and Wi-Fi scenarios, and degrades the signal and receiver sensitivity. If the antenna can receive a lower power level, its sensitivity improves.

One way to counteract this is to have the antenna and RFFE components in the shark fin on the roof, as close to the signal input as possible andbeforeany cabling. By integrating the RFFE close to the antenna, you can minimize the NF and improve signal performance — and keeping NF low also helps receiver sensitivity.

The same approach can work to improve the transmit function of the antenna too. Reducing the cabling and putting the power amplifier (PA) closest to the antenna will help reduce insertion loss and power. If you need more power on the transmit side before sending the signal, you can also use a compensator in the shark fin to amplify the signal and compensate for the loss and link budget caused by the cable lengths.

Thermal management

在车辆中，关键的关键设计挑战之一是温度，无论是车内还是在外部环境中。车辆产品变热，这些温度升高影响系统级RF调谐和性能。

所有无线连接和电子设备仍然居住在同一小型车辆占地面积内。这意味着在限制区域中增加辐射热量。热量也会影响可靠性，这可能会损害汽车中的安全性。

When trying to mitigate thermal issues, key parameters to keep your eye on include:

• rffe效率
• Current consumption
• Power dissipation

设计人员提供的一些热耗散方法传导和对流冷却，但这些是在汽车中使用的有限。进一步使这种热攻击变得更复杂的是小产品形状因子。以下技术可以帮助管理与热量相关的RF问题：

电池寿命

In 2017, theJ.D. Power Vehicle Dependability Studyreported that for the first time, battery failure was among the list of top ten problems facing car owners. According to their findings, the battery is the most frequently replaced component that isn’t related to normal wear and tear — and they’re replaced in 6.1% of 3-year-old vehicles, an increase of 1.3% from 2016. They determined that the increased current draw from many new, complex on-vehicle electronic systems (such as infotainment, smartphone connectivity, voice recognition and keyless entry) were dragging down battery life.

一个例子是车辆钥匙扣，以解锁并启动汽车。汽车所有者为方便起见使用这项技术 - 但它可以耗尽汽车电池。如果钥匙孔保持在靠近或车辆内部，则发射器和接收器继续通信，划线。测试表明，靠近车辆的钥匙扣越过电池的速度比在汽车外部留下的速度快。

As new wireless and wired technologies find their way into the automobile, it’s important to do the following to extend battery life:

• 目标设备解决方案，具有低功耗。
• 在空闲和运行时间内了解RFFE功耗。
• 使用滤波器最小或没有偏移温度。

可靠性和长期性能

The automotive electronics sector provides solid revenue growth prospects for RF semiconductor suppliers. Innovations in applications like ADAS, electric vehicles,人机界面（HMI）连接的信息娱乐是推动的半导体内容增加，汽车工程师必须让RF和其他子系统无缝地工作。这些半导体还需要满足汽车行业建立的严格可靠性要求。

It may be tempting to use a commercial part instead of a dedicated, auto-qualified product. But selecting a product designed specifically for automotive applications and that has passed IATF and IEC certification tests can help ensure your RF system will work over the long haul.

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