Power Class 2: What You Need to Know

RF engineers are continually challenged when designing RF front-ends for mobile devices. A higher number of frequency bands (up to 40), including Wi-Fi and Bluetooth, jammed into one device; fewer SKUs (stock keeping units) — all can make design tricky. In some cases, difficult coexistence requirements can go from being a minor inconvenience to a nightmare. And that's before designing for new standards, such as Power Class 2.

但是，TDD-LTE频段41没有与之相关的任何3GPP遗留技术，因此它不必向后兼容。这允许3GPP定义新的功率标准 - 功率等级2 - 并增加TDD带41的电源输出。

Power Class 2 allows for output power levels of 26 dBm — double the maximum output power previously defined by Power Class 3. (See the figure below.)

The increase in output power to Power Class 2 compensates for greater propagation losses at the higher TDD frequencies, enabling carriers to maintain cell coverage without adding expensive infrastructure. This is a win-win for both the user experience and the carriers — but it's a challenge for device manufacturers.

The RF Challenge

随着RF前端复杂性的增长，整体插入损耗链路预算增加。使用传统的离散组件和冗余匹配设计仅增加了链接预算。新的电力等级2要求（即输出功率为26 dBm）进一步使RF设计变得复杂。

在设计前端时，RF工程师需要使用以下内容：

• The best possible link budget to meet the new 26 dBm Power Class 2 standard
• 设计技术和组件以抵消插入损耗的同比增长（见下图）
• 用于缓解RF共存问题的最佳过滤器

But there's good news. From the RF front-end module perspective, analysis shows that TDD B41 at 26 dBm actually improves the PA contribution to battery life. There is also up to 30% improvement in cell coverage in B41 TD-LTE with a single carrier.

Qorvo如何接近电力等级2

作为RF设计工程师，我们必须尽可能减少这些匹配损失和系统链接预算。Qorvo使用两种策略来实现这一目标：

• Integrated modules:高性能，高度集成的RF模块，如Qorvo的rf flex™andrf fusion™allow direct matching between filters, switches and PAs, which can reduce the matching loss for both the Tx and Rx paths byas much as 0.5 dB。这有助于设计人员更接近26 dBm输出的目标，而无需将完全负担单独输出。

• Premium filter technology:RF filters that mitigate coexistence issues introduce insertion loss to the system design. The filtering challenge is to pass the desired signals while attenuating undesired spectral components. Qorvo'sBAW filter technologyprovides greater filter attenuation and superior filter insertion loss, which are required to avoid interference and optimize B41 link budgets.

Power Class 2 and Beyond

RF front-end design will continue to get more difficult as bands increase, frequencies go higher, and capacity solutions like载波聚合expand. Power Class 2 is a challenge, but one an RF engineer can meet if partnering with the most knowledgeable RF suppliers. Using high-performance QorvoBAW filter technologyand a highly integrated design approach likeRF FlexandRF Fusion将有助于手机设计师在较短的时间内更高效和成功。